Pretreatment Composition

ABSTRACT

Disclosed is a method of treating a substrate, comprising contacting at least a portion of the substrate surface with a first composition comprising a lanthanide source and an oxidizing agent. A substrate obtainable by the methods also is disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/374,188, filed on Aug. 12, 2016 and entitled “Sealing Composition”and to U.S. Provisional Application No. 62/374,199, filed Aug. 12, 2016and entitled “Pretreatment Composition”, both of which are incorporatedin their entirety herein by reference.

FIELD

The present invention relates to sealing compositions and methods fortreating a metal substrate. The present invention also relates to acoated metal substrate.

BACKGROUND

The use of protective coatings on metal substrates for improvedcorrosion resistance and paint adhesion is common. Conventionaltechniques for coating such substrates include techniques that involvepretreating the metal substrate with chromium-containing compositions.The use of such chromate-containing compositions, however, impartsenvironmental and health concerns.

As a result, chromate-free pretreatment compositions have beendeveloped. Such compositions are generally based on chemical mixturesthat react with the substrate surface and bind to it to form aprotective layer. For example, pretreatment compositions based on aGroup IIIB metal or Group IVB metal have become more prevalent. Suchcompositions often contain a source of free fluoride, i.e., fluorideavailable as isolated ions in the pretreatment composition as opposed tofluoride that is covalently or ionically bound to another elementcation, such as the Group TIM or a Group IVB metal ion or hydrogen ion.Free fluoride can etch the surface of the metal substrate, therebypromoting deposition of a Group TIM or Group IVB metal coating.Nevertheless, the corrosion resistance capability of these pretreatmentcompositions has generally been significantly inferior to conventionalchromium-containing pretreatments.

It would be desirable to provide compositions and methods for treating ametal substrate that overcome at least some of the previously describeddrawbacks of the prior art, including the environmental drawbacksassociated with the use of chromates. It also would be desirable toprovide compositions and methods for treating metal substrate thatimpart corrosion resistance properties that are equivalent to, or evensuperior to, the corrosion resistance properties imparted through theuse of phosphate- or chromium-containing conversion coatings. It wouldalso be desirable to provide related coated metal substrates.

SUMMARY

Disclosed herein is a system for treating a substrate comprising: afirst composition for contacting at least a portion of the substrate,the first composition comprising a lanthanide series element cation andan oxidizing agent.

Also disclosed herein is a method of treating a substrate comprising:contacting at least a portion of the substrate with a first compositioncomprising a lanthanide series element cation and an oxidizing agent.

Also disclosed are substrates obtainable by the system and/or methods.

BRIEF DESCRIPTION OF THE FIGURE

FIG. 1 shows a schematic illustrating thickness of a layer of the secondcomposition on a substrate surface.

FIG. 2 shows an XPS depth profile of substrate treated with L_(i)OH orL_(i2)CO₃. The two plots are averages throughout the surface withmeasurements taken 50 nm. The data indicates there is lithium present inthe 0 to 45 nm depth range.

DETAILED DESCRIPTION

As mentioned above, disclosed herein is a system comprising, or in somecases, consisting essentially of, or in some cases, consisting of, afirst composition comprising, or in some cases, consisting essentiallyof, or in some cases, consisting of, a lanthanide series element cationand an oxidizing agent. The system may further comprise, or in somecases, consist essentially of, or in some cases, consist of, a secondcomposition comprising, or in some cases, consisting essentially of, orin some cases, consisting of, a Group IA metal cation, or a thirdcomposition comprising, or in some cases, consisting essentially of, orin some cases, consisting of, a Grope IVB metal cation. The first,second, and third composition each may be a sealing composition or aconversion composition, as defined herein.

According to the method of the present invention, at least a portion ofthe substrate may be contacted with the first composition, and mayoptionally be contacted with the second composition or the thirdcomposition. According to the invention, the contacting with the firstcomposition may precede or follow the contacting with the second and/orthird composition. As described more fully herein, there may, in someinstances, there may be rinse steps that intervene the contacting withthe first composition and the second and/or third composition.

The present invention also is directed to a substrate comprising a filmformed from a pretreatment composition comprising a lanthanide serieselement source and an oxidizing agent, wherein the level of thelanthanide series element in the film is at least 100 counts greaterthan on a surface of a substrate that does not have the film thereon asmeasured by X-ray fluorescence (60 second timed assay, 15 Kv, 45 μA,filter 3, T(p)=1.5 μs).

The substrate may further comprise a film or a layer formed from theGroup IA metal cation or the Group IVB metal cation.

Suitable substrates that may be used in the present invention includemetal substrates, metal alloy substrates, and/or substrates that havebeen metallized, such as nickel plated plastic. According to the presentinvention, the metal or metal alloy can comprise or be steel, aluminum,zinc, nickel, and/or magnesium. For example, the steel substrate couldbe cold rolled steel, hot rolled steel, electrogalvanized steel, and/orhot dipped galvanized steel. Aluminum alloys of the 1XXX, 2XXX, 3XXX,4XXX, 5XXX, 6XXX, or 7XXX series as well as clad aluminum alloys alsomay be used as the substrate. Aluminum alloys may comprise 0.01% byweight copper to 10% by weight copper. Aluminum alloys which are treatedmay also include castings, such as 1XX.X, 2XX.X, 3XX.X, 4XX.X, 5XX.X,6XX.X, 7XX.X, 8XX.X, or 9XX.X (e.g.: A356.0). Magnesium alloys of theAZ31B, AZ91C, AM60B, or EV31A series also may be used as the substrate.The substrate used in the present invention may also comprise titaniumand/or titanium alloys, zinc and/or zinc alloys, and/or nickel and/ornickel alloys. According to the present invention, the substrate maycomprise a portion of a vehicle such as a vehicular body (e.g., withoutlimitation, door, body panel, trunk deck lid, roof panel, hood, roofand/or stringers, rivets, landing gear components, and/or skins used onan aircraft) and/or a vehicular frame. As used herein, “vehicle” orvariations thereof includes, but is not limited to, civilian, commercialand military aircraft, and/or land vehicles such as cars, motorcycles,and/or trucks.

First Composition

According to the present invention, the first composition may comprise alanthanide series element cation. The first composition also may furthercomprise an ion of a Group IIA metal, a Group VB metal, a Group VIBmetal, a Group VIIB metal, and/or a Group XII metal (together with thelanthanide series cation, the Group TIM metal cation, and/or the GroupIVB metal cation, referred to collectively herein as “first compositionmetal cations”).

According to the present invention, the lanthanide series metal cationmay be present in the first composition in an amount of at least 5 ppm,such as at least 150 ppm, such as at least 300 ppm, (calculated as metalcation) based on total weight of the first composition, and in someinstances may be present in the first composition in an amount of nomore than 25,000 ppm, such as no more than 12,500 ppm, such as no morethan 10,000 ppm, (calculated as metal cation) based on total weight ofthe first composition. According to the present invention, lanthanideseries metal cation may be present in the first composition in an amountof 5 ppm to 25,000 ppm, such as 150 ppm to 12,500 ppm, such as 300 ppmto 10,000 ppm, (calculated as metal cation) based on total weight of thefirst composition.

According to the present invention, the lanthanide series element cationmay, for example, comprise cerium, praseodymium, terbium, orcombinations thereof; the Group IIA metal cation may comprise magnesium;the Group IIIB metal cation may comprise yttrium, scandium, orcombinations thereof; the Group IVB metal cation may comprise zirconium,titanium, hafnium, or combinations thereof; the Group VB metal cationmay comprise vanadium; the Group VIB metal may comprise molybdenum; theGroup VIIB metal cation may comprise trivalent or hexavalent chromium ormanganese; and the Group XII metal cation may comprise zinc(collectively, the “conversion composition metal cations”).

According to the present invention, the first composition may furthercomprise an anion that may be suitable for forming a salt with the firstcomposition metal cations, such as a halogen, a nitrate, a sulfate, aphosphate, a silicate (orthosilicates and metasilicates), carbonates,hydroxides, and the like. According to the present invention, the firstcomposition metal salt may be present in the first composition in anamount of at least 50 ppm (calculated as metal salt) based on totalweight of the first composition, such as at least 1000 ppm, and in someinstances, may be present in an amount of no more than 30,000 ppm, suchas no more than 2000 ppm. According to the present invention, the firstcomposition metal salt may be present in an amount of 50 ppm to 30,000ppm, such as 1000 ppm to 2000 ppm (calculated as metal salt) based ontotal weight of the first composition.

According to the present invention, the halogen may be present in thefirst composition, if at all, in an amount of at least 5 ppm (calculatedas anion) based on total weight of the first composition, such as atleast 50 ppm, such as at least 150 ppm, such as at least 500 ppm, andmay be present in an amount of no more than 25,000 ppm (calculated asanion) based on total weight of the first composition, such as no morethan 18,500 ppm, such as no more than 4000 ppm, such as no more than2000 ppm. According to the present invention, the halogen may be presentin the first composition, if at all, in an amount of 5 ppm to 25,000 ppm(calculated as anion) based on total weight of the first composition,such as 50 ppm to 18,500 ppm, such as 150 ppm to 4000, such as 500 ppmto 2000 ppm.

According to the present invention, the nitrate may be present in thefirst composition, if at all, in an amount of at least 2 ppm (calculatedas anion) based on total weight of the first composition, such as atleast 50 ppm, such as at least 250 ppm, and may be present in an amountof no more than 10,000 ppm (calculated as anion) based on total weightof the first composition, such as no more than 5000 ppm, such as no morethan 2500 ppm. According to the present invention, the halogen may bepresent in the first composition, if at all, in an amount of 2 ppm to10,000 ppm (calculated as anion) based on total weight of the firstcomposition, such as 50 ppm to 5000 ppm, such as 250 ppm to 2500 ppm.

According to the present invention, the first composition metal cationmay be present in the first composition in an amount of at least 5 ppm,such as at least 150 ppm, such as at least 300 ppm, (calculated as metalcation) based on total weight of the first composition, and in someinstances may be present in the first composition in an amount of nomore than 25,000 ppm, such as no more than 12,500 ppm, such as no morethan 10,000 ppm, (calculated as metal cation) based on total weight ofthe first composition. According to the present invention, the firstcomposition metal cation may be present in the first composition in anamount of 5 ppm to 25,000 ppm, such as 150 ppm to 12,500 ppm, such as300 ppm to 10,000 ppm (calculated as metal cation) based on total weightof the first composition.

According to the present invention, the first composition may comprisean oxidizing agent. Non-limiting examples of the oxidizing agent includeperoxides, persulfates, perchlorates, hypochlorite, nitric acid, spargedoxygen, bromates, peroxi-benzoates, ozone, or combinations thereof.

According to the present invention, the oxidizing agent may be presentin an amount of at least 100 ppm, such as at least 500 ppm, based ontotal weight of the first composition, and in some instances, may bepresent in an amount of no more than 13,000 ppm, such as no more than3000 ppm, based on total weight of the first composition. In someinstances, the oxidizing agent may be present in the first compositionin an amount of 100 ppm to 13,000 ppm, such as 500 ppm to 3000 ppm,based on total weight of the first composition.

According to the present invention, the first composition may excludechromium or chromium-containing compounds. As used herein, the term“chromium-containing compound” refers to materials that includehexavalent chromium. Non-limiting examples of such materials includechromic acid, chromium trioxide, chromic acid anhydride, dichromatesalts, such as ammonium dichromate, sodium dichromate, potassiumdichromate, and calcium, barium, magnesium, zinc, cadmium, and strontiumdichromate. When a composition and/or a coating or a layer,respectively, formed from the same is substantially free, essentiallyfree, or completely free of chromium, this includes chromium in anyform, such as, but not limited to, the hexavalent chromium-containingcompounds listed above.

Thus, optionally, according to the present invention, the firstcompositions and/or coatings or layers, respectively, deposited from thesame may be substantially free, may be essentially free, and/or may becompletely free of one or more of any of the elements or compoundslisted in the preceding paragraph. A first composition and/or coating orlayer, respectively, formed from the same that is substantially free ofchromium or derivatives thereof means that chromium or derivativesthereof are not intentionally added, but may be present in traceamounts, such as because of impurities or unavoidable contamination fromthe environment. In other words, the amount of material is so small thatit does not affect the properties of the conversion composition; in thecase of chromium, this may further include that the element or compoundsthereof are not present in the first compositions and/or coatings orlayers, respectively, formed from the same in such a level that itcauses a burden on the environment. The term “substantially free” meansthat the compositions and/or coating or layers, respectively, formedfrom the same contain less than 10 ppm of any or all of the elements orcompounds listed in the preceding paragraph, based on total weight ofthe composition or the layer, respectively, if any at all. The term“essentially free” means that the conversion compositions and/orcoatings or layers, respectively, formed from the same contain less than1 ppm of any or all of the elements or compounds listed in the precedingparagraph, if any at all. The term “completely free” means that thecompositions and/or coatings or layers, respectively, formed from thesame contain less than 1 ppb of any or all of the elements or compoundslisted in the preceding paragraph, if any at all.

According to the present invention, the first composition may, in someinstances, exclude phosphate ions or phosphate-containing compoundsand/or the formation of sludge, such as aluminum phosphate, ironphosphate, and/or zinc phosphate, formed in the case of using a treatingagent based on zinc phosphate. As used herein, “phosphate-containingcompounds” include compounds containing the element phosphorous such asortho phosphate, pyrophosphate, metaphosphate, tripolyphosphate,organophosphonates, and the like, and can include, but are not limitedto, monovalent, divalent, or trivalent cations such as: sodium,potassium, calcium, zinc, nickel, manganese, aluminum and/or iron. Whena composition and/or a layer or coating comprising the same issubstantially free, essentially free, or completely free of phosphate,this includes phosphate ions or compounds containing phosphate in anyform.

Thus, according to the present invention, composition and/or layersdeposited from the same may be substantially free, or in some cases maybe essentially free, or in some cases may be completely free, of one ormore of any of the ions or compounds listed in the preceding paragraph.A composition and/or layers deposited from the same that issubstantially free of phosphate means that phosphate ions or compoundscontaining phosphate are not intentionally added, but may be present intrace amounts, such as because of impurities or unavoidablecontamination from the environment. In other words, the amount ofmaterial is so small that it does not affect the properties of thecomposition; this may further include that phosphate is not present inthe conversion compositions and/or layers deposited from the same insuch a level that they cause a burden on the environment. The term“substantially free” means that the compositions and/or layers depositedfrom the same contain less than 5 ppm of any or all of the phosphateanions or compounds listed in the preceding paragraph, based on totalweight of the composition or the layer, respectively, if any at all. Theterm “essentially free” means that the conversion compositions and/orlayers comprising the same contain less than 1 ppm of any or all of thephosphate anions or compounds listed in the preceding paragraph. Theterm “completely free” means that the compositions and/or layerscomprising the same contain less than 1 ppb of any or all of thephosphate anions or compounds listed in the preceding paragraph, if anyat all.

Optionally, according to the present invention, the first compositionmay contain no more than one lanthanide series element and/or no morethan one lanthanide series element source, such that the firstcomposition may contain one lanthanide series element and/or a singlelanthanide series element source, and in some instances, may besubstantially free, or in some instances, essentially free, or in someinstances, completely free, of more than one lanthanide series elementand/or more than one lanthanide series element source.

In some instances, the first composition according to the presentinvention may be substantially free, or, in some cases, completely freeof gelatin, such as, but not limited to, bovine, porcine, or fish.

In some instances, the first composition according to the presentinvention may be substantially free, or, in some cases, completely freeof oxides. As used herein, the term “substantially free,” when used withrespect to oxides in the first composition, means that oxides are notpurposefully added to the first composition, and, if present at all,only is present in the pretreatment composition in a trace amount of 5ppm or less, based on a total weight of the composition. As used herein,the term “essentially free,” when used with respect to oxides in thefirst composition, means that if oxide is present at all in the firstcomposition, only is present in the pretreatment composition in anamount of 1 ppm or less, based on a total weight of the composition. Asused herein, the term “completely free,” when used with respect to oxidein the first composition, means that oxide is present in thepretreatment composition in an amount of 1 ppb or less, based on a totalweight of the composition.

According to the present invention, the pH of the first composition maybe 1.0 to 4.5, such as 3 to 4, and may be adjusted using, for example,any acid and/or base as is necessary. According to the presentinvention, the pH of the first composition may be maintained through theinclusion of an acidic material, including water soluble and/or waterdispersible acids, such as nitric acid, sulfuric acid, and/or phosphoricacid. According to the present invention, the pH of the composition maybe maintained through the inclusion of a basic material, including watersoluble and/or water dispersible bases, such as sodium hydroxide, sodiumcarbonate, potassium hydroxide, ammonium hydroxide, ammonia, and/oramines such as triethylamine, methylethyl amine, or mixtures thereof.

The first composition may comprise an aqueous medium and may optionallycontain other materials such as nonionic surfactants and auxiliariesconventionally used in the art of conversion compositions. In theaqueous medium, water dispersible organic solvents, for example,alcohols with up to about 8 carbon atoms such as methanol, isopropanol,and the like, may be present; or glycol ethers such as the monoalkylethers of ethylene glycol, diethylene glycol, or propylene glycol, andthe like. When present, water dispersible organic solvents are typicallyused in amounts up to about ten percent by volume, based on the totalvolume of aqueous medium.

Other optional materials include surfactants that function as defoamersor substrate wetting agents. Anionic, cationic, amphoteric, and/ornonionic surfactants may be used. Defoaming surfactants may optionallybe present at levels up to 1 weight percent, such as up to 0.1 percentby weight, and wetting agents are typically present at levels up to 2percent, such as up to 0.5 percent by weight, based on the total weightof the first composition.

The first composition may comprise a carrier, often an aqueous medium,so that the composition is in the form of a solution or dispersion ofthe lanthanide and/or Group IIIB metal cation in the carrier. In theseembodiments, the solution or dispersion may be brought into contact withthe substrate by any of a variety of known techniques, such as dippingor immersion, spraying, intermittent spraying, dipping followed byspraying, spraying followed by dipping, brushing, or roll-coating.According to the invention, the solution or dispersion when applied tothe metal substrate is at a temperature ranging from 40° F. to 160° F.,such as 60° F. to 110° F., such as 70° F. to 90° F. For example, theconversion process may be carried out at ambient or room temperature.The contact time is often from 1 second to 15 minutes, such as 4 minutesto 10 minutes, such as 5 seconds to 4 minutes.

According to the present invention, following the contacting with thefirst composition, the substrate optionally may be dried in place, e.g.,air dried at room temperature or be dried with hot air, for example, byusing an air knife, by flashing off the water by brief exposure of thesubstrate to a high temperature, such as by drying the substrate in anoven at 15° C. to 100° C., such as 20° C. to 90° C., or in a heaterassembly using, for example, infrared heat, such as for 10 minutes at70° C., or by passing the substrate between squeegee rolls. According tothe present invention, the substrate surface may be partially, or insome instances, completely dried prior to any subsequent contact of thesubstrate surface with any water, solutions, compositions, or the like.As used herein with respect to a substrate surface, “completely dry” or“completely dried” means there is no moisture on the substrate surfacevisible to the human eye. According to the present invention, followingthe contacting with the first composition, the substrate (either wet ordried in place) optionally may be rinsed with tap water, deionizedwater, and/or an aqueous solution of rinsing agents in order to removeany residue and then optionally may be dried, for example air dried ordried with hot air as described in the preceding sentence. According tothe present invention, such water rinses may be eliminated and thesubstrate (either wet or dried in place) may be contacted withsubsequent treatment compositions.

Optionally, a substrate (wet or dried as described above) treated withthe first composition (and optionally with second or third compositionsor electrocaot, powder coat or liquid coatings described herein) may beheated in an oven or heater such as ones described above at atemperature of 100 C to 240 C, such as 110 C to 232 C. It has beensurprisingly discovered that such substrates have a b* value of lessthan 3.09 (spectral component excluded, 25 mm aperture).

Second Composition Comprising a Group IA Metal Cation

According to the present invention, the second composition may comprisea Group IA metal cation, such as a lithium cation, which may be in theform of a salt. In addition, the second composition also may furthercomprise at least one Group IA metal cation other than lithium, a GroupVB metal cation, and/or Group VIB metal cation. The at least one GroupIA metal cation other than lithium, a Group VB metal cation, and/orGroup VIB metal cation may be in the form of a salt. Nonlimitingexamples of anions suitable for forming a salt with the lithium, GroupIA cations other than lithium, Group VB cations, and/or Group VIBcations include carbonates, hydroxides, nitrates, halogens, sulfates,phosphates and silicates (e.g., orthosilicates and metasilicates) suchthat the metal salt may comprise a carbonate, an hydroxide, a nitrate, ahalide, a sulfate, a phosphate, a silicate (e.g., orthosilicate ormetasilicate), a permanganate, a chromate, a vanadate, a molybdate,and/or a perchlorate.

According to the present invention, the metal salts of the secondcomposition (i.e., the salts of lithium, Group IA metals other thanlithium, Group VB, and/or Group VIB) each may be present in the secondcomposition in an amount of at least 25 ppm, such as at least 150 ppm,such as at least 500 ppm (calculated as total compound) based on totalweight of the second composition, and in some instances, no more than30000 ppm, such as no more than 2000 ppm, such as no more than 1500 ppm(calculated as total compound) based on total weight of the secondcomposition. According to the present invention, the metal salts of thesecond composition (i.e., the salts of lithium, Group IA metals otherthan lithium, Group VB, and/or Group VIB) each may be present in thesecond composition in an amount of 25 ppm to 30000 ppm, such as 150 ppmto 2000 ppm, such as 500 ppm to 1500 (calculated as total compound)based on total weight of the second composition.

According to the present invention, the lithium cation, the Group IAcation other than lithium, the Group VB metal cation, and the Group VIBmetal cation each may be present in the second composition in an amountof at least 5 ppm, such as at least 50 ppm, such as at least 150 ppm,such as at least 250 ppm (calculated as cation) based on total weight ofthe second composition, and in some instances, may be present in anamount of no more than 5500 ppm, such as no more than 1200 ppm, such asno more than 1000 ppm, such as no more than 500 ppm, (calculated ascation) based on total weight of the second composition. In someinstances, according to the present invention, the lithium cation, theGroup IA cation other than lithium, the Group VB metal cation, and theGroup VIB metal cation each may be present in the second composition inan amount of 5 ppm to 5500 ppm, such as 50 ppm to 1000 ppm, (calculatedas cation) based on total weight of the second composition, such as 150ppm to 500 ppm.

According to the present invention, the lithium salt of the presentinvention may comprise an inorganic lithium salt, an organic lithiumsalt, or combinations thereof. According to the present invention, theanion and the cation of the lithium salt both may be soluble in water.According to the present invention, for example, the lithium salt mayhave a solubility constant in water at a temperature of 25° C. (K; 25°C.) of at least 1×10⁻¹¹, such as least 1×10⁻¹¹, and in some instances,may be no more than 5×10⁺². According to the present invention, thelithium salt may have a solubility constant in water at a temperature of25° C. (K; 25° C.) of 1×10⁻¹¹ to 5×10⁺², such as 1×10⁻⁴ to 5×10⁺². Asused herein, “solubility constant” means the product of the equilibriumconcentrations of the ions in a saturated aqueous solution of therespective lithium salt. Each concentration is raised to the power ofthe respective coefficient of ion in the balanced equation. Thesolubility constants for various salts can be found in the Handbook ofChemistry and Physics.

According to the present invention, the second composition of thepresent invention may an include oxidizing agent, such as hydrogenperoxide, persulfates, perchlorates, sparged oxygen, bromates,peroxi-benzoates, ozone, and the like, or combinations thereof. Forexample, the second composition may comprise 0.1 wt % to 15 wt % of anoxidizing agent based on total weight of the second composition, such as2 wt % to 10 wt %, such as 6 wt % to 8 wt %. Alternatively, according tothe present invention, the second composition may be substantially free,or in some cases, essentially free, or in some cases, completely free,of an oxidizing agent.

According to the present invention, the second composition may excludeGroup IIA metal cations or Group IIA metal-containing compounds,including but not limited to calcium. Non-limiting examples of suchmaterials include Group IIA metal hydroxides, Group IIA metal nitrates,Group IIA metal halides, Group IIA metal sulfamates, Group IIA metalsulfates, Group IIA carbonates and/or Group IIA metal carboxylates. Whena second composition and/or a coating or a layer, respectively, formedfrom the same is substantially free, essentially free, or completelyfree of a Group IIA metal cation, this includes Group IIA metal cationsin any form, such as, but not limited to, the Group IIA metal-containingcompounds listed above.

According to the present invention, the second composition may excludechromium or chromium-containing compounds. As used herein, the term“chromium-containing compound” refers to materials that includehexavalent chromium. Non-limiting examples of such materials includechromic acid, chromium trioxide, chromic acid anhydride, dichromatesalts, such as ammonium dichromate, sodium dichromate, potassiumdichromate, and calcium, barium, magnesium, zinc, cadmium, and strontiumdichromate. When a second composition and/or a coating or a layer,respectively, formed from the same is substantially free, essentiallyfree, or completely free of chromium, this includes chromium in anyform, such as, but not limited to, the hexavalent chromium-containingcompounds listed above.

Thus, optionally, according to the present invention, the present secondcompositions and/or coatings or layers, respectively, deposited from thesame may be substantially free, may be essentially free, and/or may becompletely free of one or more of any of the elements or compoundslisted in the preceding paragraph. A second composition and/or coatingor layer, respectively, formed from the same that is substantially freeof chromium or derivatives thereof means that chromium or derivativesthereof are not intentionally added, but may be present in traceamounts, such as because of impurities or unavoidable contamination fromthe environment. In other words, the amount of material is so small thatit does not affect the properties of the second composition; in the caseof chromium, this may further include that the element or compoundsthereof are not present in the second compositions and/or coatings orlayers, respectively, formed from the same in such a level that itcauses a burden on the environment. The term “substantially free” meansthat the second compositions and/or coating or layers, respectively,formed from the same contain less than 10 ppm of any or all of theelements or compounds listed in the preceding paragraph, based on totalweight of the composition or the layer, respectively, if any at all. Theterm “essentially free” means that the second compositions and/orcoatings or layers, respectively, formed from the same contain less than1 ppm of any or all of the elements or compounds listed in the precedingparagraph, if any at all. The term “completely free” means that thesecond compositions and/or coatings or layers, respectively, formed fromthe same contain less than 1 ppb of any or all of the elements orcompounds listed in the preceding paragraph, if any at all.

According to the present invention, the second composition may, in someinstances, exclude phosphate ions or phosphate-containing compoundsand/or the formation of sludge, such as aluminum phosphate, ironphosphate, and/or zinc phosphate, formed in the case of using a treatingagent based on zinc phosphate. As used herein, “phosphate-containingcompounds” include compounds containing the element phosphorous such asortho phosphate, pyrophosphate, metaphosphate, tripolyphosphate,organophosphonates, and the like, and can include, but are not limitedto, monovalent, divalent, or trivalent cations such as: sodium,potassium, calcium, zinc, nickel, manganese, aluminum and/or iron. Whena composition and/or a layer or coating comprising the same issubstantially free, essentially free, or completely free of phosphate,this includes phosphate ions or compounds containing phosphate in anyform.

Thus, according to the present invention, second composition and/orlayers deposited from the same may be substantially free, or in somecases may be essentially free, or in some cases may be completely free,of one or more of any of the ions or compounds listed in the precedingparagraph. A second composition and/or layers deposited from the samethat is substantially free of phosphate means that phosphate ions orcompounds containing phosphate are not intentionally added, but may bepresent in trace amounts, such as because of impurities or unavoidablecontamination from the environment. In other words, the amount ofmaterial is so small that it does not affect the properties of thecomposition; this may further include that phosphate is not present inthe second compositions and/or layers deposited from the same in such alevel that they cause a burden on the environment. The term“substantially free” means that the second compositions and/or layersdeposited from the same contain less than 5 ppm of any or all of thephosphate anions or compounds listed in the preceding paragraph, basedon total weight of the composition or the layer, respectively, if any atall. The term “essentially free” means that the second compositionsand/or layers comprising the same contain less than 1 ppm of any or allof the phosphate anions or compounds listed in the preceding paragraph.The term “completely free” means that the second compositions and/orlayers comprising the same contain less than 1 ppb of any or all of thephosphate anions or compounds listed in the preceding paragraph, if anyat all.

According to the present invention, the second composition may, in someinstances, exclude fluoride or fluoride sources. As used herein,“fluoride sources” include monofluorides, bifluorides, fluoridecomplexes, and mixtures thereof known to generate fluoride ions. When acomposition and/or a layer or coating comprising the same issubstantially free, essentially free, or completely free of fluoride,this includes fluoride ions or fluoride sources in any form, but doesnot include unintentional fluoride that may be present in a bath as aresult of, for example, carry-over from prior treatment baths in theprocessing line, municipal water sources (e.g.: fluoride added to watersupplies to prevent tooth decay), fluoride from a pretreated substrate,or the like. That is, a bath that is substantially free, essentiallyfree, or completely free of fluoride, may have unintentional fluoridethat may be derived from these external sources, even though thecomposition used to make the bath prior to use on the processing linewas substantially free, essentially free, or completely free offluoride.

For example, the second composition may be substantially free of anyfluoride-sources, such as ammonium and alkali metal fluorides, acidfluorides, fluoroboric, fluorosilicic, fluorotitanic, and fluorozirconicacids and their ammonium and alkali metal salts, and other inorganicfluorides, nonexclusive examples of which are: zinc fluoride, zincaluminum fluoride, titanium fluoride, zirconium fluoride, nickelfluoride, ammonium fluoride, sodium fluoride, potassium fluoride, andhydrofluoric acid, as well as other similar materials known to thoseskilled in the art.

Fluoride present in the second composition that is not bound to metalsions such as Group IVB metal ions, or hydrogen ion, defined herein as“free fluoride,” may be measured as an operational parameter in thesecond composition bath using, for example, an Orion Dual Star DualChannel Benchtop Meter equipped with a fluoride ion selective electrode(“ISE”) available from Thermoscientific, the Symphony® Fluoride IonSelective Combination Electrode supplied by VWR International, orsimilar electrodes. See, e.g., Light and Cappuccino, Determination offluoride in toothpaste using an ion-selective electrode, J. Chem. Educ.,52:4, 247-250, April 1975. The fluoride ISE may be standardized byimmersing the electrode into solutions of known fluoride concentrationand recording the reading in millivolts, and then plotting thesemillivolt readings in a logarithmic graph. The millivolt reading of anunknown sample can then be compared to this calibration graph and theconcentration of fluoride determined. Alternatively, the fluoride ISEcan be used with a meter that will perform the calibration calculationsinternally and thus, after calibration, the concentration of the unknownsample can be read directly.

Fluoride ion is a small negative ion with a high charge density, so inaqueous solution it is frequently complexed with metal ions having ahigh positive charge density, such as Group IVB metal ions, or withhydrogen ion. Fluoride anions in solution that are ionically orcovalently bound to metal cations or hydrogen ion are defined herein as“bound fluoride.” The fluoride ions thus complexed are not measurablewith the fluoride ISE unless the solution they are present in is mixedwith an ionic strength adjustment buffer (e.g.: citrate anion or EDTA)that releases the fluoride ions from such complexes. At that point (allof) the fluoride ions are measurable by the fluoride ISE, and themeasurement is known as “total fluoride”. Alternatively, the totalfluoride can be calculated by comparing the weight of the fluoridesupplied in the sealer composition by the total weight of thecomposition.

According to the present invention, the treatment composition may, insome instances, be substantially free, or in some instances, essentiallyfree, or in some instances, completely free, of cobalt ions orcobalt-containing compounds. As used herein, “cobalt-containingcompounds” include compounds, complexes or salts containing the elementcobalt such as, for example, cobalt sulfate, cobalt nitrate, cobaltcarbonate and cobalt acetate. When a composition and/or a layer orcoating comprising the same is substantially free, essentially free, orcompletely free of cobalt, this includes cobalt ions or compoundscontaining cobalt in any form.

According to the present invention, the treatment composition may, insome instances, be substantially free, or in some instances, essentiallyfree, or in some instances, completely free, of vanadium ions orvanadium-containing compounds. As used herein, “vanadium-containingcompounds” include compounds, complexes or salts containing the elementvanadium such as, for example, vanadates and decavanadates that includecounterions of alkali metal or ammonium cations, including, for example,sodium ammonium decavanadate. When a composition and/or a layer orcoating comprising the same is substantially free, essentially free, orcompletely free of vanadium, this includes vanadium ions or compoundscontaining vanadium in any form.

Optionally, the second composition of the present invention may furthercomprise a nitrogen-containing heterocyclic compound. Thenitrogen-containing heterocyclic compound may include cyclic compoundshaving 1 nitrogen atom, such as pyrroles, and azole compounds having 2or more nitrogen atoms, such as pyrazoles, imidazoles, triazoles,tetrazoles and pentazoles, 1 nitrogen atom and 1 oxygen atom, such asoxazoles and isoxazoles, or 1 nitrogen atom and 1 sulfur atom, such asthiazoles and isothiazoles. Nonlimiting examples of suitable azolecompounds include 2,5-dimercapto-1,3,4-thiadiazole (CAS:1072-71-5),1H-benzotriazole (CAS: 95-14-7), 1H-1,2,3-triazole (CAS: 288-36-8),2-amino-5-mercapto-1,3,4-thiadiazole (CAS: 2349-67-9), also named5-amino-1,3,4-thiadiazole-2-thiol, and 2-amino-1,3,4-thiadiazole (CAS:4005-51-0). In some embodiments, for example, the azole compoundcomprises 2,5-dimercapto-1,3,4-thiadiazole. Additionally, according tothe present invention, the nitrogen-containing heterocyclic compound maybe in the form of a salt, such as a sodium salt.

The nitrogen-containing heterocyclic compound may be present in thesecond composition at a concentration of at least 0.0005 g per liter ofcomposition, such as at least 0.0008 g per liter of composition, such asat least 0.002 g per liter of composition, and in some instances, may bepresent in the second composition in an amount of no more than 3 g perliter of composition, such as no more than 0.2 g per liter ofcomposition, such as no more than 0.1 g per liter of composition.According to the present invention, the nitrogen-containing heterocycliccompound may be present in the second composition (if at all) at aconcentration of 0.0005 g per liter of composition to 3 g per liter ofcomposition, such as 0.0008 g per liter of composition to 0.2 g perliter of composition, such as 0.002 g per liter of composition to 0.1 gper liter of composition.

According to the present invention, the second composition may comprisean aqueous medium and optionally may contain other materials such as atleast one organic solvent. Nonlimiting examples of suitable suchsolvents include propylene glycol, ethylene glycol, glycerol, lowmolecular weight alcohols, and the like. When present, if at all, theorganic solvent may be present in the second composition in an amount ofat least 1 g solvent per liter of second composition, such as at leastabout 2 g solvent per liter of second solution, and in some instances,may be present in an amount of no more than 40 g solvent per liter ofsecond composition, such as no more than 20 g solvent per liter ofsecond solution. According to the present invention, the organic solventmay be present in the second composition, if at all, in an amount of 1 gsolvent per liter of second composition to 40 g solvent per liter ofsecond composition, such as 2 g solvent per liter of second compositionto 20 g solvent per liter of second composition.

According to the present invention, the pH of the second composition maybe at least 8, such as at least 9, such as at least 10, such as at least11, and in some instances may be no higher than 13, such as no higherthan 12, such as no higher than 11.5. According to the presentinvention, the pH of the second composition may be 8 to 13, such as 10to 12, such as 11 to 11.5. The pH of the second composition may beadjusted using, for example, any acid and/or base as is necessary.According to the present invention, the pH of the second composition maybe maintained through the inclusion of an acidic material, includingcarbon dioxide, water soluble and/or water dispersible acids, such ashydrochloric acid, nitric acid, sulfuric acid, and/or phosphoric acid.According to the present invention, the pH of the second composition maybe maintained through the inclusion of a basic material, including watersoluble and/or water dispersible bases, including carbonates such asGroup I carbonates, Group II carbonates, hydroxides such as lithiumhydroxide, sodium hydroxide, potassium hydroxide, or ammonium hydroxide,ammonia, and/or amines such as triethylamine, methylethyl amine, ormixtures thereof.

As mentioned above, the second composition may comprise a carrier, oftenan aqueous medium, so that the composition is in the form of a solutionor dispersion of the lithium cation in the carrier. According to thepresent invention, the solution or dispersion may be brought intocontact with the substrate by any of a variety of known techniques, suchas dipping or immersion, spraying, intermittent spraying, dippingfollowed by spraying, spraying followed by dipping, brushing, orroll-coating. According to the invention, the solution or dispersionwhen applied to the metal substrate may be at a temperature ranging from40° F. to about 160° F., such as 60° F. to 110° F. For example, theprocess of contacting the metal substrate with the second compositionmay be carried out at ambient or room temperature. The contact time isoften from about 1 second to about 15 minutes, such as about 5 secondsto about 2 minutes.

According to the present invention, following the contacting with thesecond composition, the substrate optionally may be dried in place,e.g., air dried at room temperature or be dried with hot air, forexample, by using an air knife, by flashing off the water by briefexposure of the substrate to a high temperature, such as by drying thesubstrate in an oven at 15° C. to 100° C., such as 20° C. to 90° C., orin a heater assembly using, for example, infrared heat, such as for 10minutes at 70° C., or by passing the substrate between squeegee rolls.According to the present invention, the substrate surface may bepartially, or in some instances, completely dried prior to anysubsequent contact of the substrate surface with any water, solutions,compositions, or the like. As used herein with respect to a substratesurface, “completely dry” or “completely dried” means there is nomoisture on the substrate surface visible to the human eye. According tothe present invention, following the contacting with the secondcomposition, the substrate (either wet or dried in place) optionally maybe rinsed with tap water, deionized water, and/or an aqueous solution ofrinsing agents in order to remove any residue and then optionally may bedried, for example air dried or dried with hot air as described in thepreceding sentence. Acording to the present invention, such water rinsesmay be eliminated and the substrate (either wet or dried in place) maybe contacted with subsequent treatment compositions.

Optionally, according to the present invention, following the contactingwith the second composition, the substrate optionally is not rinsed orcontacted with any aqueous solutions prior to contacting at least aportion of the substrate surface with subsequent treatment compositionsto form films, layers, and/or coatings thereon (described below).

Optionally, according to the present invention, following the contactingwith the second composition, the substrate optionally may be contactedwith tap water, deionized water, RO water and/or any aqueous solutionknown to those of skill in the art of substrate treatment, wherein suchwater or aqueous solution may be at a temperature of room temperature(60° F.) to 212° F. The substrate then optionally may be dried, forexample air dried or dried with hot air as described in the precedingparagraph such that the substrate surface may be partially, or in someinstances, completely dried prior to any subsequent contact of thesubstrate surface with any water, solutions, compositions, or the like.

FIG. 2 shows an XPS survey scan of a substrate surface treated withlithium hydroxide or lithium carbonate and confirms that no lithium wasdetected at the substrate surface. The substrate had approximately a 2.2□m thick oxidized aluminum on aluminum-copper alloy (as determined byTEM). According to the present invention, the thickness of the layerformed by the treatment composition may for instance be up to 550 nm,such as 5 nm to 550 nm, such as 10 nm to 400 nm, such as 25 nm to 250nm. Thickness of layer formed from the treatment composition can bedetermined using a handful of analytical techniques including, but notlimited to XPS (x-ray photoelectron spectroscopy) depth profiling or TEM(transmission electron microscopy). As used herein, “thickness,” whenused with respect to a layer formed by the second composition of thepresent invention comprising a Group IA metal cation, refers to either(a) a layer formed above the original air/substrate interface, (b) amodified layer formed below the pretreatment/substrate interface, or (c)a combination of (a) and (b), as illustrated in FIG. 1. Althoughmodified layer (b) is shown extending to the pretreatment/substrateinterface in FIG. 1, an intervening layer may be present between themodified layer (b) and the pretreatment/substrate interface. Likewise,(c), a combination of (a) and (b), is not limited to a continuous layerand may include multiple layers with intervening layers therebetween,and the measurement of the thickness of layer (c) may exclude theintervening layers.

Third Composition Comprising a Group IVB Metal Cation

As mentioned above, the system and method of the present invention maycomprise a third composition comprising a Group IVB metal cation. Thethird composition also may further comprise a Group IA metal cationand/or a Group VIB metal cation (together with the Group IVB metalcation, referred to collectively herein as “third composition metalcations”).

According to the present invention, the Group IA metal cation maycomprise lithium; the Group IVB metal cation may comprise zirconium,titanium, hafnium, or combinations thereof; and the Group VIB metal maycomprise molybdenum.

For example, the Group IVB metal cation used in the third compositionmay be a compound of zirconium, titanium, hafnium, or a mixture thereof.Suitable compounds of zirconium include, but are not limited to,hexafluorozirconic acid, alkali metal and ammonium salts thereof,ammonium zirconium carbonate, zirconyl nitrate, zirconyl sulfate,zirconium carboxylates and zirconium hydroxy carboxylates, such aszirconium acetate, zirconium oxalate, ammonium zirconium glycolate,ammonium zirconium lactate, ammonium zirconium citrate, zirconium basiccarbonate, and mixtures thereof. Suitable compounds of titanium include,but are not limited to, fluorotitanic acid and its salts. A suitablecompound of hafnium includes, but is not limited to, hafnium nitrate.

According to the present invention, the Group IVB metal cation may bepresent in the third composition in a total amount of at least 20 ppmmetal (calculated as metal cation), based on total weight of the thirdcomposition, such as at least 50 ppm metal, or, in some cases, at least70 ppm metal. According to the present invention, the Group IVB metalmay be present in the third composition in a total amount of no morethan 1000 ppm metal (calculated as metal cation), based on total weightof the third composition, such as no more than 600 ppm metal, or, insome cases, no more than 300 ppm metal. According to the presentinvention, the Group IVB metal cation may be present in the thirdcomposition in a total amount of 20 ppm metal to 1000 ppm metal(calculated as metal cation), based on total weight of the thirdcomposition, such as from 50 ppm metal to 600 ppm metal, such as from 70ppm metal to 300 ppm metal. As used herein, the term “total amount,”when used with respect to the amount of Group IVB metal cation, meansthe sum of all Group IV metals present in the third composition.

According to the present invention, the third composition also maycomprise a Group IA metal cation such as a lithium cation. According tothe invention, the source of Group IA metal cation in the thirdcomposition may be in the form of a salt. Non-limiting examples ofsuitable lithium salts include lithium nitrate, lithium sulfate, lithiumfluoride, lithium chloride, lithium hydroxide, lithium carbonate,lithium iodide, and combinations thereof.

According to the present invention, the Group I metal cation may bepresent in the third composition in an amount of at least 2 ppm (asmetal cation), based on a total weight of the third composition, such asat least 5 ppm, such as at least 25 ppm, such as at least 75 ppm, and insome instances, may be present in amount of no more than 500 ppm (asmetal cation), based on a total weight of the third composition, such asno more than 250 ppm, such as no more than 125 ppm, such as no more than100 ppm. According to the present invention, the Group IA metal cationmay be present in the third composition in an amount of 2 ppm to 500 ppm(as metal cation), based on a total weight of the third composition,such as 5 ppm to 250 ppm, such as 5 ppm to 125 ppm, such as 5 ppm to 25ppm. The amount of Group IA metal cation in the third composition canrange between the recited values inclusive of the recited values.

According to the present invention, the third composition may alsocomprise a Group VIB metal cation. According to the present invention,the source of Group VIB metal cation in the third composition may be inthe form of a salt. Non-limiting examples of suitable molybdenum saltsinclude sodium molybdate, lithium molybdate, calcium molybdate,potassium molybdate, ammonium molybdate, molybdenum chloride, molybdenumacetate, molybdenum sulfamate, molybdenum formate, molybdenum lactate,and combinations thereof.

According to the present invention, the Group VIB metal cation may bepresent in the third composition in an amount of at least 5 ppm (asmetal cation), based on a total weight of the third composition, such asat least 25 ppm, such as 100 ppm, and in some instances, may be presentin the third composition in an amount of no more than 500 ppm (as metalcation), based on total weight of the third composition, such as no morethan 250 ppm, such as no more than 150 ppm. According to the presentinvention, the Group VIB metal cation may be present in the thirdcomposition in an amount of 5 ppm to 500 ppm (as metal cation), based ontotal weight of the third composition, such as 25 ppm to 250 ppm, suchas 40 ppm to 120 ppm. The amount of Group VIB metal cation in the thirdcomposition can range between the recited values inclusive of therecited values.

According to the present invention, the third composition may furthercomprise an anion that may be suitable for forming a salt with the thirdcomposition metal cations, such as a halogen, a nitrate, a sulfate, asilicate (orthosilicates and metasilicates), carbonates, hydroxides, andthe like.

According to the present invention, the nitrate may be present in thethird composition, if at all, in an amount of at least 2 ppm, such as atleast 50 ppm, such as at least 50 ppm, (calculated as nitrate anion)based on total weight of the third composition, and may be present in anamount of no more than 10,000 ppm, such as no more than 5000 ppm, suchas no more than 2500 ppm, (calculated as nitrate anion) based on totalweight of the third composition. According to the present invention, thehalogen may be present in the third composition, if at all, in an amountof 2 ppm to 10,000 ppm, such as 25 ppm to 5000 ppm, such as 50 ppm to2500 ppm, (calculated as nitrate anion) based on total weight of thethird composition.

According to the present invention, the third composition also maycomprise an electropositive metal ion. As used herein, the term“electropositive metal ion” refers to metal ions that will be reduced bythe metal substrate being treated when the third solution contacts thesurface of the metallic substrate. As will be appreciated by one skilledin the art, the tendency of chemical species to be reduced is called thereduction potential, is expressed in volts, and is measured relative tothe standard hydrogen electrode, which is arbitrarily assigned areduction potential of zero. The reduction potential for severalelements is set forth in Table 1 below (according to the CRC 82^(nd)Edition, 2001-2002). An element or ion is more easily reduced thananother element or ion if it has a voltage value, E*, in the followingtable, that is more positive than the elements or ions to which it isbeing compared.

TABLE 1 Reduction half- Element cell reaction Voltage, E* Potassium K⁺ +e → K −2.93 Calcium Ca²⁺ + 2e → Ca −2.87 Sodium Na⁺ + e → Na −2.71Magnesium Mg²⁺ + 2e → Mg −2.37 Aluminum Al³⁺ + 3e → Al −1.66 Zinc Zn²⁺ +2e → Zn −0.76 Iron Fe²⁺ + 2e → Fe −0.45 Nickel Ni²⁺ + 2e → Ni −0.26 TinSn²⁺ + 2e → Sn −0.14 Lead Pb²⁺ + 2e → Pb −0.13 Hydrogen 2H⁺ + 2e → H₂−0.00 Copper Cu²⁺ + 2e → Cu 0.34 Mercury Hg₂ ²⁺ + 2e → 2Hg 0.80 SilverAg⁺ + e → Ag 0.80 Gold Au³⁺ + 3e → Au 1.50

Thus, as will be apparent, when the metal substrate comprises one of thematerials listed earlier, such as cold rolled steel, hot rolled steel,steel coated with zinc metal, zinc compounds, or zinc alloys, hot-dippedgalvanized steel, galvanealed steel, steel plated with zinc alloy,aluminum alloys, aluminum plated steel, aluminum alloy plated steel,magnesium and magnesium alloys, suitable electropositive metal ions fordeposition thereon include, for example, nickel, copper, silver, andgold, as well mixtures thereof.

According to the present invention, when the electropositive metal ioncomprises copper, both soluble and insoluble compounds may serve as asource of copper ions in the third compositions. For example, thesupplying source of copper ions in the third composition may be a watersoluble copper compound. Specific examples of such compounds include,but are not limited to, copper sulfate, copper nitrate, copperthiocyanate, disodium copper ethylenediaminetetraacetate tetrahydrate,copper bromide, copper oxide, copper hydroxide, copper chloride, copperfluoride, copper gluconate, copper citrate, copper lauroyl sarcosinate,copper lactate, copper oxalate, copper tartrate, copper malate, coppersuccinate, copper malonate, copper maleate, copper benzoate, coppersalicylate, copper amino acid complexes, copper fumarate, copperglycerophosphate, sodium copper chlorophyllin, copper fluorosilicate,copper fluoroborate and copper iodate, as well as copper salts ofcarboxylic acids such as in the homologous series formic acid todecanoic acid, and copper salts of polybasic acids in the series oxalicacid to suberic acid.

When copper ions supplied from such a water-soluble copper compound areprecipitated as an impurity in the form of copper sulfate, copper oxide,etc., it may be desirable to add a complexing agent that suppresses theprecipitation of copper ions, thus stabilizing them as a copper complexin the composition.

According to the present invention, the copper compound may be added asa copper complex salt such as or Cu-EDTA, which can be present stably inthe third composition on its own, but it is also possible to form acopper complex that can be present stably in the third composition bycombining a complexing agent with a compound that is difficult tosolubilize on its own. An example thereof includes a Cu-EDTA complexformed by a combination of CuSO₄ and EDTA.2Na.

According to the present invention, the electropositive metal ion may bepresent in the third composition in an amount of at least 2 ppm(calculated as metal ion), based on the total weight of the thirdcomposition, such as at least 4 ppm, such as at least 6 ppm, such as atleast 8 ppm, such as at least 10 ppm. According to the presentinvention, the electropositive metal ion may be present in the thirdcomposition in an amount of no more than 100 ppm (calculated as metalion), based on the total weight of the third composition, such as nomore than 80 ppm, such as no more than 60 ppm, such as no more than 40ppm, such as no more than 20 ppm. According to the present invention,the electropositive metal ion may be present in the third composition inan amount of from 2 ppm to 100 ppm (calculated as metal ion), based onthe total weight of the third composition, such as from 4 ppm to 80 ppm,such as from 6 ppm to 60 ppm, such as from 8 ppm to 40 ppm, The amountof electropositive metal ion in the third composition can range betweenthe recited values inclusive of the recited values.

According to the present invention, a source of fluoride may be presentin the third composition. As used herein the amount of fluoridedisclosed or reported in the third composition is referred to as “freefluoride,” as measured in part per millions of fluoride. Free fluorideis defined herein as being able to be measured by a fluoride-selectiveISE. In addition to free fluoride, a third may also contain “boundfluoride, which is described above. The sum of the concentrations of thebound and free fluoride equal the total fluoride, which can bedetermined as described herein. The total fluoride in the thirdcomposition can be supplied by hydrofluoric acid, as well as alkalimetal and ammonium fluorides or hydrogen fluorides. Additionally, totalfluoride in the third composition may be derived from Group IVB metalspresent in the third composition, including, for example,hexafluorozirconic acid or hexafluorotitanic acid. Other complexfluorides, such as H₂SiF₆ or HBF₄, can be added to the third compositionto supply total fluoride. The skilled artisan will understand that thepresence of free fluoride in the third bath can impact third depositionand etching of the substrate, hence it is critical to measure this bathparameter. The levels of free fluoride will depend on the pH and theaddition of chelators into the third bath and indicates the degree offluoride association with the metal ions/protons present in the thirdbath. For example, third compositions of identical total fluoride levelscan have different free fluoride levels which will be influenced by thepH and chelators present in the third solution.

According to the present invention, the free fluoride of the thirdcomposition may be present in an amount of at least 15 ppm, based on atotal weight of the third composition, such as at least 50 ppm freefluoride, such as at least 100 ppm free fluoride, such as at least 200ppm free fluoride. According to the present invention, the free fluorideof the third composition may be present in an amount of no more than2500 ppm, based on a total weight of the third composition, such as nomore than 1000 ppm free fluoride, such as no more than 500 ppm freefluoride, such as no more than 250 ppm free fluoride. According to thepresent invention, the free fluoride of the third composition may bepresent in an amount of 15 ppm free fluoride to 2500 ppm free fluoride,based on a total weight of the third composition, such as 50 ppmfluoride to 1000 ppm, such as no more than 200 ppm free fluoride to 500ppm free fluoride, such as no more than 100 ppm free fluoride to 250 ppmfree fluoride.

The third composition may further comprise an amino compound. The aminocompound can be primary, secondary, tertiary, or quaternary amine.Specific examples of the alpha amino compounds can be sarcosine, glycineand oleyl imidazoline. According to the present invention, the alphaamino acid compound may be a substituted or an unsubstituted glycine.The substituted glycine can be sarcosine, iminodiacetic acid, leucine ortyrosine. Illustrative but non-limiting examples of the beta amino acidcompounds include taurine and N-methyl taurine. An illustrative butnon-limiting example of the gamma amino acid compound includes gammaaminobutyric acid. Illustrative but non-limiting examples of the cyclicamino compound having an amine group and an acid group on the same ringinclude aminobenzoic acid and derivatives thereof. Illustrative butnon-limiting examples of the beta amino alcohol compounds includesimidazoline and derivatives thereof, choline, triethanolamine, diethanolglycine and 2-amino-2-ethyl-1,3-propanediol. An illustrative butnon-limiting example of the gamma amino alcohol compounds includesaminopropanol. Illustrative but non-limiting examples of the cyclicamino compounds having an amine group and a hydroxyl group on the samering includes amino phenols and derivatives thereof.

The amino compound may be present in the third composition in an amountof at least 50 ppm based on total weight of the third composition suchas at least 100 ppm, and in some instances may be present in an amountof no more than 100,000 ppm, such as no more than 10,000 ppm. Accordingto the present invention, the amino compound may be present in the thirdcomposition in an amount of 50 ppm to 100,000 ppm based on total weightof the third composition, such as 100 ppm to 10,000 ppm.

According to the present invention, the third composition may, in someinstances, comprise an oxidizing agent. Non-limiting examples of theoxidizing agent include peroxides, persulfates, perchlorates, chlorates,hypochlorite, nitric acid, sparged oxygen, bromates, peroxi-benzoates,ozone, or combinations thereof. According to the present invention, theoxidizing agent may be present, if at all, in an amount of at least 50ppm, such as at least 500 ppm, based on total weight of the thirdcomposition, and in some instances, may be present in an amount of nomore than 13,000 ppm, such as no more than 3000 ppm, based on totalweight of the third composition. In some instances, the oxidizing agentmay be present in the third composition, if at all, in an amount of 100ppm to 13,000 ppm, such as 500 ppm to 3000 ppm, based on total weight ofthe third composition. As used herein, the term “oxidizing agent,” whenused with respect to a component of the third composition, refers to achemical which is capable of oxidizing at least one of: a metal presentin the substrate which is contacted by the third composition, and/or ametal-complexing agent present in the third composition. As used hereinwith respect to “oxidizing agent,” the phrase “capable of oxidizing”means capable of removing electrons from an atom or a molecule presentin the substrate or the third composition, as the case may be, therebydecreasing the number of electrons of such atom or molecule.

According to the present invention, the third composition may excludechromium or chromium-containing compounds. As used herein, the term“chromium-containing compound” refers to materials that includetrivalent and/or hexavalent chromium. Non-limiting examples of suchmaterials include chromic acid, chromium trioxide, chromic acidanhydride, dichromate salts, such as ammonium dichromate, sodiumdichromate, potassium dichromate, and calcium, barium, magnesium, zinc,cadmium, strontium dichromate, chromium(III) sulfate, chromium(III)chloride, and chromium(III) nitrate. When a third composition and/or acoating or a layer, respectively, formed from the same is substantiallyfree, essentially free, or completely free of chromium, this includeschromium in any form, such as, but not limited to, the trivalent andhexavalent chromium-containing compounds listed above.

Thus, optionally, according to the present invention, the present thirdcompositions and/or coatings or layers, respectively, deposited from thesame may be substantially free, may be essentially free, and/or may becompletely free of one or more of any of the elements or compoundslisted in the preceding paragraph. A third composition and/or coating orlayer, respectively, formed from the same that is substantially free ofchromium or derivatives thereof means that chromium or derivativesthereof are not intentionally added, but may be present in traceamounts, such as because of impurities or unavoidable contamination fromthe environment. In other words, the amount of material is so small thatit does not affect the properties of the third composition; in the caseof chromium, this may further include that the element or compoundsthereof are not present in the third compositions and/or coatings orlayers, respectively, formed from the same in such a level that itcauses a burden on the environment. The term “substantially free” meansthat the third compositions and/or coating or layers, respectively,formed from the same contain less than 10 ppm of any or all of theelements or compounds listed in the preceding paragraph, based on totalweight of the composition or the layer, respectively, if any at all. Theterm “essentially free” means that the third compositions and/orcoatings or layers, respectively, formed from the same contain less than1 ppm of any or all of the elements or compounds listed in the precedingparagraph, if any at all. The term “completely free” means that thethird compositions and/or coatings or layers, respectively, formed fromthe same contain less than 1 ppb of any or all of the elements orcompounds listed in the preceding paragraph, if any at all.

According to the present invention, the third composition may, in someinstances, exclude phosphate ions or phosphate-containing compoundsand/or the formation of sludge, such as aluminum phosphate, ironphosphate, and/or zinc phosphate, formed in the case of using a treatingagent based on zinc phosphate. As used herein, “phosphate-containingcompounds” include compounds containing the element phosphorous such asortho phosphate, pyrophosphate, metaphosphate, tripolyphosphate,organophosphonates, and the like, and can include, but are not limitedto, monovalent, divalent, or trivalent cations such as: sodium,potassium, calcium, zinc, nickel, manganese, aluminum and/or iron. Whena composition and/or a layer or coating comprising the same issubstantially free, essentially free, or completely free of phosphate,this includes phosphate ions or compounds containing phosphate in anyform.

Thus, according to the present invention, third composition and/orlayers deposited from the same may be substantially free, or in somecases may be essentially free, or in some cases may be completely free,of one or more of any of the ions or compounds listed in the precedingparagraph. A third composition and/or layers deposited from the samethat is substantially free of phosphate means that phosphate ions orcompounds containing phosphate are not intentionally added, but may bepresent in trace amounts, such as because of impurities or unavoidablecontamination from the environment. In other words, the amount ofmaterial is so small that it does not affect the properties of thecomposition; this may further include that phosphate is not present inthe third compositions and/or layers deposited from the same in such alevel that they cause a burden on the environment. The term“substantially free” means that the third compositions and/or layersdeposited from the same contain less than 5 ppm of any or all of thephosphate anions or compounds listed in the preceding paragraph, basedon total weight of the composition or the layer, respectively, if any atall. The term “essentially free” means that the third compositionsand/or layers comprising the same contain less than 1 ppm of any or allof the phosphate anions or compounds listed in the preceding paragraph.The term “completely free” means that the third compositions and/orlayers comprising the same contain less than 1 ppb of any or all of thephosphate anions or compounds listed in the preceding paragraph, if anyat all.

Optionally, according to the present invention, the third compositionmay further comprise a source of phosphate ions. For clarity, when usedherein, “phosphate ions” refers to phosphate ions that derive from ororiginate from inorganic phosphate compounds. For example, in someinstances, phosphate ions may be present in an amount of greater than 5ppm, based on total weight of the third composition, such as 10 ppm,such as 20 ppm. In some instances, phosphate ions may be present in anamount of no more than 60 ppm, based on total weight of the thirdcomposition, such as no more than 40 ppm, such as no more than 30 ppm.In some instances, phosphate ions may be present in an amount of from 5ppm to 60 ppm, based on total weight of the third composition, such asfrom 10 ppm to 40 ppm, such as from 20 ppm to 30 ppm.

According to the present invention, the pH of the third composition maybe 6.5 or less, such as 5.5 or less, such as 4.5 or less, such as 3.5 orless. According to the present invention, the pH of the thirdcomposition may, in some instances, be 2.0 to 6.5, such as 3 to 4.5, andmay be adjusted using, for example, any acid and/or base as isnecessary. According to the present invention, the pH of the thirdcomposition may be maintained through the inclusion of an acidicmaterial, including water soluble and/or water dispersible acids, suchas nitric acid, sulfuric acid, and/or phosphoric acid. According to thepresent invention, the pH of the composition may be maintained throughthe inclusion of a basic material, including water soluble and/or waterdispersible bases, such as sodium hydroxide, sodium carbonate, potassiumhydroxide, ammonium hydroxide, ammonia, and/or amines such astriethylamine, methylethyl amine, or mixtures thereof.

According to the present invention, the third composition also mayfurther comprise a resinous binder. Suitable resins include reactionproducts of one or more alkanolamines and an epoxy-functional materialcontaining at least two epoxy groups, such as those disclosed in U.S.Pat. No. 5,653,823. In some cases, such resins contain beta hydroxyester, imide, or sulfide functionality, incorporated by usingdimethylolpropionic acid, phthalimide, or mercaptoglycerine as anadditional reactant in the preparation of the resin. Alternatively, thereaction product can for instance be that of the diglycidyl ether ofBisphenol A (commercially available e.g. from Shell Chemical Company asEPON 880), dimethylol propionic acid, and diethanolamine in a 0.6 to5.0:0.05 to 5.5:1 mole ratio. Other suitable resinous binders includewater soluble and water dispersible polyacrylic acids such as thosedisclosed in U.S. Pat. Nos. 3,912,548 and 5,328,525; phenol formaldehyderesins such as those described in U.S. Pat. No. 5,662,746; water solublepolyamides such as those disclosed in WO 95/33869; copolymers of maleicor acrylic acid with allyl ether such as those described in Canadianpatent application 2,087,352; and water soluble and dispersible resinsincluding epoxy resins, aminoplasts, phenol-formaldehyde resins,tannins, and polyvinyl phenols such as those discussed in U.S. Pat. No.5,449,415

According to the present invention, the resinous binder often may bepresent in the third composition in an amount of 0.005 percent to 30percent by weight, such as 0.5 to 3 percent by weight, based on thetotal weight of the composition. Alternatively, according to the presentinvention, the third composition may be substantially free or, in somecases, completely free of any resinous binder. As used herein, the term“substantially free”, when used with reference to the absence ofresinous binder in the third composition, means that, if present at all,any resinous binder is present in the third composition in a traceamount of less than 0.005 percent by weight, based on total weight ofthe composition. As used herein, the term “completely free” means thatthere is no resinous binder in the third composition at all.

The third composition may comprise an aqueous medium and may optionallycontain other materials such as nonionic surfactants and auxiliariesconventionally used in the art of third compositions. In the aqueousmedium, water dispersible organic solvents, for example, alcohols withup to about 8 carbon atoms such as methanol, isopropanol, and the like,may be present; or glycol ethers such as the monoalkyl ethers ofethylene glycol, diethylene glycol, or propylene glycol, and the like.When present, water dispersible organic solvents are typically used inamounts up to about ten percent by volume, based on the total volume ofaqueous medium.

Other optional materials include surfactants that function as defoamersor substrate wetting agents. Anionic, cationic, amphoteric, and/ornonionic surfactants may be used. Defoaming surfactants may optionallybe present at levels up to 1 weight percent, such as up to 0.1 percentby weight, and wetting agents are typically present at levels up to 2percent, such as up to 0.5 percent by weight, based on the total weightof the third composition.

Optionally, according to the present invention, the third compositionand/or films deposited or formed therefrom may further comprise silicon,such as silanes, silicas, silicates, and the like, in amounts of atleast 10 ppm, based on total weight of the third composition, such as atleast 20 ppm, such as at least 50 ppm. According to the presentinvention, the third composition and/or films deposited or formedtherefrom may comprise silicon in amounts of less than 500 ppm, based ontotal weight of the third composition, such as less than 250 ppm, suchas less than 100 ppm. According to the present invention, the thirdcomposition and/or films deposited or formed therefrom may comprisesilicon in amounts of 10 ppm to 500 ppm, based on total weight of thethird composition, such as 20 ppm to 250 ppm, such as 50 ppm to 100 ppm.Alternatively, the third composition of the present invention and/orfilms deposited or formed therefrom may be substantially free, or, insome cases, completely free of silicon.

The third composition may comprise a carrier, often an aqueous medium,so that the composition is in the form of a solution or dispersion ofthe Group IVB metal in the carrier. According to the present invention,the solution or dispersion may be brought into contact with thesubstrate by any of a variety of known techniques, such as dipping orimmersion, spraying, intermittent spraying, dipping followed byspraying, spraying followed by dipping, brushing, or roll-coating.According to the invention, the solution or dispersion when applied tothe metal substrate is at a temperature ranging from 40° F. to 185° F.,such as 60° F. to 110° F., such as 70° F. to 90° F. For example, thethird process may be carried out at ambient or room temperature. Thecontact time is often from 5thirds to 15 minutes, such as 10 thirds to10 minutes, such as 15 thirds to 3 minutes.

Following the contacting with the third composition, the substrate maybe rinsed with tap water, deionized water, and/or an aqueous solution ofrinsing agents in order to remove any residue. The substrate optionallymay be air dried at room temperature or may be dried with hot air, forexample, by using an air knife, by flashing off the water by briefexposure of the substrate to a high temperature, such as by drying thesubstrate in an oven at 15° C. to 200° C., such as 20° C. to 90° C., orin a heater assembly using, for example, infrared heat, such as for 10minutes at 70° C., or by passing the substrate between squeegee rolls.According to the present invention, following the contacting with thethird composition, the substrate optionally may be rinsed with tapwater, deionized water, and/or an aqueous solution of rinsing agents inorder to remove any residue and then optionally may be dried, forexample air dried or dried with hot air as described in the precedingsentence.

According to the present invention the film coverage of the residue ofthe third coating composition generally ranges typically from 1 to 1000milligrams per square meter (mg/m²), for example, from 10 to 400 mg/m².The thickness of the third coating may for instance be less than 1micrometer, for example from 1 to 500 nanometers, or from 10 to 300nanometers. Coating weights may be determined by removing the film fromthe substrate and determining the elemental composition using a varietyof analytical techniques (such as XRF, ICP, etc.). Pretreatmentthickness can be determined using a handful of analytical techniquesincluding, but not limited to XPS depth profiling or TEM.

Additional Components of the System and Method of the Present Invention

According to the present invention, at least a portion of the substratesurface may be cleaned and/or deoxidized prior to contacting at least aportion of the substrate surface with one of the compositions describedabove, in order to remove grease, dirt, and/or other extraneous matter.At least a portion of the surface of the substrate may be cleaned byphysical and/or chemical means, such as mechanically abrading thesurface and/or cleaning/degreasing the surface with commerciallyavailable alkaline or acidic cleaning agents that are well known tothose skilled in the art. Examples of alkaline cleaners suitable for usein the present invention include Chemkleen™ 166HP, 166M/C, 177, 490MX,2010LP, and Surface Prep 1 (SP1), Ultrax 32, Ultrax 97, Ultrax 29, andUltrax92D, each of which are commercially available from PPG Industries,Inc. (Cleveland, Ohio), and any of the DFM Series, RECC 1001, and88X1002 cleaners commercially available from PRC-DeSoto International,Sylmar, Calif.), and Turco 4215-NCLT and Ridolene (commerciallyavailable from Henkel Technologies, Madison Heights, Mich.). Suchcleaners are often preceded or followed by a water rinse, such as withtap water, distilled water, or combinations thereof.

As mentioned above, according to the present invention, at least aportion of the cleaned substrate surface may be deoxidized, mechanicallyand/or chemically. As used herein, the term “deoxidize” means removal ofthe oxide layer found on the surface of the substrate in order topromote uniform deposition of the conversion composition (describedbelow), as well as to promote the adhesion of the conversion compositioncoating to the substrate surface. Suitable deoxidizers will be familiarto those skilled in the art. A typical mechanical deoxidizer may beuniform roughening of the substrate surface, such as by using a scouringor cleaning pad. Typical chemical deoxidizers include, for example,acid-based deoxidizers such as phosphoric acid, nitric acid, fluoroboricacid, sulfuric acid, chromic acid, hydrofluoric acid, and ammoniumbifluoride, or Amchem 7/17 deoxidizers (available from HenkelTechnologies, Madison Heights, Mich.), OAKITE DEOXIDIZER LNC(commercially available from Chemetall), TURCO DEOXIDIZER 6(commercially available from Henkel), or combinations thereof. Often,the chemical deoxidizer comprises a carrier, often an aqueous medium, sothat the deoxidizer may be in the form of a solution or dispersion inthe carrier, in which case the solution or dispersion may be broughtinto contact with the substrate by any of a variety of known techniques,such as dipping or immersion, spraying, intermittent spraying, dippingfollowed by spraying, spraying followed by dipping, brushing, orroll-coating. According to the present invention, the skilled artisanwill select a temperature range of the solution or dispersion, whenapplied to the metal substrate, based on etch rates, for example, at atemperature ranging from 50° F. to 150° F. (10° C. to 66° C.), such asfrom 70° F. to 130° F. (21° C. to 54° C.), such as from 80° F. to 120°F. (27° C. to 49° C.). The contact time may be from 30 seconds to 20minutes, such as 1 minute to 15 minutes, such as 90 seconds to 12minutes, such as 3 minutes to 9 minutes.

Following the cleaning and/or deoxidizing step(s), the substrateoptionally may be rinsed with tap water, deionized water, and/or anaqueous solution of rinsing agents in order to remove any residue.According to the present invention, the wet substrate surface may betreated with a conversion composition (described below) and/or a sealingcomposition (described above), or the substrate may be dried prior totreating the substrate surface, such as air dried, for example, by usingan air knife, by flashing off the water by brief exposure of thesubstrate to a high temperature, such as 15° C. to 100° C., such as 20°C. to 90° C., or in a heater assembly using, for example, infrared heat,such as for 10 minutes at 70° C., or by passing the substrate betweensqueegee rolls.

As mentioned above, at least a portion of the substrate surfaceoptionally may be contacted with a second or a third composition priorto or after being contacted with the first composition of the presentinvention.

Color measurements can be determined for substrates treated with thefirst composition (cerium) to characterize the degree of yellowing ofthe treated substrate. Color parameters may be determined using an XriteCi7800 Benchtop Sphere Spectrophotometer, 25 mm aperture available fromX-Rite, Incorporated, Grandville, Mich. or such similar instruments. TheXrite Ci7800 instrument measures according to the L*a*b* color spacetheory. The term b* indicates a more yellow hue for positive values anda more blue hue for negative values. The term a* indicates a more greenhue when negative and a more red hue when positive. The term L*indicates a black hue when L*=0 and a white hue when L*=100.

According to the present invention, substrate that was pretreated withthe first composition had b* values that typically range from 9 to 15.Application of a heating step significantly reduced the b* value ofsubstrate contacted with the first composition, for example, a b* valuethat ranges from −20 to +8, such −15 to +5, such as −10 to +4, such as−5 to +2.5. Substrate treated according to the present invention mayhave a YI-E313 (yellow index) as determined by ASTM E313-00 of, forexample, +5 to +22 prior to heating and after heat treatment, of +2 to+10, such +3 to +9, such as +4 to +8.

The effect of heating a panel after contacting with a cerium-containingcomposition has minimal effect on the values of a* and L*. Values fora*, regardless of heat treatment will range from −15 to +15, such as −10to +10, such as −5 to +5. L* values, regardless of heat treatment willrange from 50 to 90, such as 60 to 80.

According to the present invention, disclosed herein is a substratecomprising, or in some instances consisting essentially of, or in someinstances consisting of: a film formed from a pretreatment compositioncomprising, or in some cases consisting essentially of, or in someinstances consisting of, a lanthanide and an oxidizing agent, whereinthe level of the lanthanide in the film is at least 100 counts greaterthan on a surface of a substrate that does not have the film thereon asmeasured by X-ray fluorescence (60 second timed assay, 15Kv, 45 μA,filter 3, T(p)=1.5 μs).

According to the present invention, the level of the lanthanide serieselement in the film formed on the substrate surface from thepretreatment composition is at least 100 counts greater than on asurface of a substrate that does not have the film thereon as measuredby X-ray fluorescence (60 second timed assay, 15Kv, 45 μA, filter 3,T(p)=1.5 μs). For example, the lanthanide series element may be presentin the film formed on the substrate surface, as shown by counts ofgreater than 340 counts, such as greater than 500 counts, such asgreater than 1000 counts, such as greater than 1200 counts, as measuredby X-ray fluorescence (60 second timed assay, 15Kv, 45 μA, filter 3,T(p)=1.5 μs). It has been surprisingly discovered herein thatpretreatment of a sanded substrate with the pretreatment composition ofthe present invention surprisingly resulted in superior corrosionperformance compared to an unsanded substrate pretreated withconventional pretreatment composition.

According to the present invention, the substrate having the film formedfrom the pretreatment composition has at least a 5% decrease in scribecreep on the substrate surface compared to a substrate treated with azirconium-containing pretreatment further including lithium andmolybdenum (ASTM-B 368-09 Copper Acetic Acid Salt Spray, 480 hours).

It has been surprisingly discovered that, whereas a cured electrocoatedpanel treated with a zirconium-containing pretreatment composition isvisibly yellow to the naked eye, in contrast, a cured electrocoatedpanel treated with a lanthanide-containing pretreatment composition isnot visibly yellow to the naked eye. This result was unexpected.

Furthermore, also surprisingly, it has been discovered that heating asubstrate pretreated with the conversion composition of the presentinvention at a temperature of 110 C to 232 C surprisingly reduced theyellowing seen on unheated panels pretreated with the conversioncomposition of the present invention. For example, it has beensurprisingly discovered that the b* value and YI-E313 value of panels(sanded and unsanded) treated with the conversion composition of thepresent invention were significantly reduced when such panels werepretreated with the conversion composition of the present invention, andwere even further reduced when such panels were heated at a temperatureof 110 C to 232 C.

It also has been surprisingly discovered that an electrocoated panelpretreated with a pretreatment composition comprising cerium results ina 27% reduction in the scribe creep following 480 hours exposure tocopper acetic salt spray (ASTM-B 368-09) compared to an electrocoatedpanel pretreated with a zirconium-containing pretreatment. This resultwas unexpected.

It also has been surprisingly discovered that an electrocoated panelpretreated with a pretreatment composition comprising cerium results ina 65% reduction in the scribe creep following 480 hours exposure tocopper acetic salt spray (ASTM-B 368-09) compared to an electrocoatedpanel pretreated with a zinc phosphate pretreatment. This result wasunexpected.

According to the present invention, the coating composition may comprisea thermosetting film-forming resin or a thermoplastic film-formingresin. As used herein, the term “film-forming resin” refers to resinsthat can form a self-supporting continuous film on at least a horizontalsurface of a substrate upon removal of any diluents or carriers presentin the composition or upon curing at ambient or elevated temperature.Conventional film-forming resins that may be used include, withoutlimitation, those typically used in automotive OEM coating compositions,automotive refinish coating compositions, industrial coatingcompositions, architectural coating compositions, coil coatingcompositions, and aerospace coating compositions, among others. As usedherein, the term “thermosetting” refers to resins that “set”irreversibly upon curing or crosslinking, wherein the polymer chains ofthe polymeric components are joined together by covalent bonds. Thisproperty is usually associated with a cross-linking reaction of thecomposition constituents often induced, for example, by heat orradiation. Curing or crosslinking reactions also may be carried outunder ambient conditions. Once cured or crosslinked, a thermosettingresin will not melt upon the application of heat and is insoluble insolvents. As used herein, the term “thermoplastic” refers to resins thatcomprise polymeric components that are not joined by covalent bonds andthereby can undergo liquid flow upon heating and are soluble insolvents.

As previously indicated, according to the present invention, anelectrodepositable coating composition comprising a water-dispersible,ionic salt group-containing film-forming resin that may be depositedonto the substrate by an electrocoating step wherein theelectrodepositable coating composition is deposited onto the metalsubstrate by electrodeposition.

The ionic salt group-containing film-forming polymer may comprise acationic salt group containing film-forming polymer for use in acationic electrodepositable coating composition. As used herein, theterm “cationic salt group-containing film-forming polymer” refers topolymers that include at least partially neutralized cationic groups,such as sulfonium groups and ammonium groups, that impart a positivecharge. The cationic salt group-containing film-forming polymer maycomprise active hydrogen functional groups, including, for example,hydroxyl groups, primary or secondary amine groups, and thiol groups.Cationic salt group-containing film-forming polymers that compriseactive hydrogen functional groups may be referred to as activehydrogen-containing, cationic salt group-containing film-formingpolymers. Examples of polymers that are suitable for use as the cationicsalt group-containing film-forming polymer include, but are not limitedto, alkyd polymers, acrylics, polyepoxides, polyamides, polyurethanes,polyureas, polyethers, and polyesters, among others.

The cationic salt group-containing film-forming polymer may be presentin the cationic electrodepositable coating composition in an amount of40% to 90% by weight, such as 50% to 80% by weight, such as 60% to 75%by weight, based on the total weight of the resin solids of theelectrodepositable coating composition. As used herein, the “resinsolids” include the ionic salt group-containing film-forming polymer,curing agent, and any additional water-dispersible non-pigmentedcomponent(s) present in the electrodepositable coating composition.

Alternatively, the ionic salt group containing film-forming polymer maycomprise an anionic salt group containing film-forming polymer for usein an anionic electrodepositable coating composition. As used herein,the term “anionic salt group containing film-forming polymer” refers toan anionic polymer comprising at least partially neutralized anionicfunctional groups, such as carboxylic acid and phosphoric acid groupsthat impart a negative charge. The anionic salt group-containingfilm-forming polymer may comprise active hydrogen functional groups.Anionic salt group-containing film-forming polymers that comprise activehydrogen functional groups may be referred to as activehydrogen-containing, anionic salt group-containing film-formingpolymers.

The anionic salt group-containing film-forming polymer may comprisebase-solubilized, carboxylic acid group-containing film-forming polymerssuch as the reaction product or adduct of a drying oil or semi-dryingfatty acid ester with a dicarboxylic acid or anhydride; and the reactionproduct of a fatty acid ester, unsaturated acid or anhydride and anyadditional unsaturated modifying materials which are further reactedwith polyol. Also suitable are the at least partially neutralizedinterpolymers of hydroxy-alkyl esters of unsaturated carboxylic acids,unsaturated carboxylic acid and at least one other ethylenicallyunsaturated monomer. Still another suitable anionic electrodepositableresin comprises an alkyd-aminoplast vehicle, i.e., a vehicle containingan alkyd resin and an amine-aldehyde resin. Another suitable anionicelectrodepositable resin composition comprises mixed esters of aresinous polyol. Other acid functional polymers may also be used such asphosphatized polyepoxide or phosphatized acrylic polymers. Exemplaryphosphatized polyepoxides are disclosed in U.S. Patent ApplicationPublication No. 2009-0045071 at [0004]-[0015] and U.S. patentapplication Ser. No. 13/232,093 at [0014]-[0040], the cited portions ofwhich being incorporated herein by reference.

The anionic salt group-containing film-forming polymer may be present inthe anionic electrodepositable coating composition in an amount 50% to90%, such as 55% to 80%, such as 60% to 75%, based on the total weightof the resin solids of the electrodepositable coating composition.

The electrodepositable coating composition may further comprise a curingagent. The curing agent may react with the reactive groups, such asactive hydrogen groups, of the ionic salt group-containing film-formingpolymer to effectuate cure of the coating composition to form a coating.Non-limiting examples of suitable curing agents are at least partiallyblocked polyisocyanates, aminoplast resins and phenoplast resins, suchas phenolformaldehyde condensates including allyl ether derivativesthereof.

The curing agent may be present in the cationic electrodepositablecoating composition in an amount of 10% to 60% by weight, such as 20% to50% by weight, such as 25% to 40% by weight, based on the total weightof the resin solids of the electrodepositable coating composition.Alternatively, the curing agent may be present in the anionicelectrodepositable coating composition in an amount of 10% to 50% byweight, such as 20% to 45% by weight, such as 25% to 40% by weight,based on the total weight of the resin solids of the electrodepositablecoating composition.

The electrodepositable coating composition may further comprise otheroptional ingredients, such as a pigment composition and, if desired,various additives such as fillers, plasticizers, anti-oxidants,biocides, UV light absorbers and stabilizers, hindered amine lightstabilizers, defoamers, fungicides, dispersing aids, flow controlagents, surfactants, wetting agents, or combinations thereof.

The electrodepositable coating composition may comprise water and/or oneor more organic solvent(s). Water can for example be present in amountsof 40% to 90% by weight, such as 50% to 75% by weight, based on totalweight of the electrodepositable coating composition. If used, theorganic solvents may typically be present in an amount of less than 10%by weight, such as less than 5% by weight, based on total weight of theelectrodepositable coating composition. The electrodepositable coatingcomposition may in particular be provided in the form of an aqueousdispersion. The total solids content of the electrodepositable coatingcomposition may be from 1% to 50% by weight, such as 5% to 40% byweight, such as 5% to 20% by weight, based on the total weight of theelectrodepositable coating composition. As used herein, “total solids”refers to the non-volatile content of the electrodepositable coatingcomposition, i.e., materials which will not volatilize when heated to110° C. for 15 minutes.

The cationic electrodepositable coating composition may be depositedupon an electrically conductive substrate by placing the composition incontact with an electrically conductive cathode and an electricallyconductive anode, with the surface to be coated being the cathode.Alternatively, the anionic electrodepositable coating composition may bedeposited upon an electrically conductive substrate by placing thecomposition in contact with an electrically conductive cathode and anelectrically conductive anode, with the surface to be coated being theanode. An adherent film of the electrodepositable coating composition isdeposited in a substantially continuous manner on the cathode or anode,respectively, when a sufficient voltage is impressed between theelectrodes. The applied voltage may be varied and can be, for example,as low as one volt to as high as several thousand volts, such as between50 and 500 volts. Current density is usually between 1.0 ampere and 15amperes per square foot (10.8 to 161.5 amperes per square meter) andtends to decrease quickly during the electrodeposition process,indicating formation of a continuous self-insulating film.

Once the cationic or anionic electrodepositable coating composition iselectrodeposited over at least a portion of the electroconductivesubstrate, the coated substrate is heated to a temperature and for atime sufficient to cure the electrodeposited coating on the substrate.For cationic electrodeposition, the coated substrate may be heated to atemperature ranging from 110° C. to 232° C., such as from 275° F. to400° F. (135° C. to 204.4° C.), such as from 300° F. to 360° F. (149° C.to 180° C.). For anionic electrodeposition, the coated substrate may beheated to a temperature ranging from 200° F. to 450° F. (93° C. to232.2° C.), such as from 275° F. to 400° F. (135° C. to 204.4° C.), suchas from 300° F. to 360° F. (149° C. to 180° C.), such as 200° F. to210.2° F. (93° C. to 99° C.). The curing time may be dependent upon thecuring temperature as well as other variables, for example, the filmthickness of the electrodeposited coating, level and type of catalystpresent in the composition and the like. For example, the curing timecan range from 10 minutes to 60 minutes, such as 20 to 40 minutes. Thethickness of the resultant cured electrodeposited coating may range from2 to 50 microns.

Alternatively, as mentioned above, according to the present invention,after the substrate has been contacted with the sealing composition, apowder coating composition may then be deposited onto at least a portionof the surface of the substrate. As used herein, “powder coatingcomposition” refers to a coating composition which is completely free ofwater and/or solvent. Accordingly, the powder coating compositiondisclosed herein is not synonymous to waterborne and/or solvent-bornecoating compositions known in the art.

According to the present invention, the powder coating composition maycomprise (a) a film forming polymer having a reactive functional group;and (b) a curing agent that is reactive with the functional group.Examples of powder coating compositions that may be used in the presentinvention include the polyester-based ENVIROCRON line of powder coatingcompositions (commercially available from PPG Industries, Inc.) orepoxy-polyester hybrid powder coating compositions. Alternative examplesof powder coating compositions that may be used in the present inventioninclude low temperature cure thermosetting powder coating compositionscomprising (a) at least one tertiary aminourea compound, at least onetertiary aminourethane compound, or mixtures thereof, and (b) at leastone film-forming epoxy-containing resin and/or at least onesiloxane-containing resin (such as those described in U.S. Pat. No.7,470,752, assigned to PPG Industries, Inc. and incorporated herein byreference); curable powder coating compositions generally comprising (a)at least one tertiary aminourea compound, at least one tertiaryaminourethane compound, or mixtures thereof, and (b) at least onefilm-forming epoxy-containing resin and/or at least onesiloxane-containing resin (such as those described in U.S. Pat. No.7,432,333, assigned to PPG Industries, Inc. and incorporated herein byreference); and those comprising a solid particulate mixture of areactive group-containing polymer having a T_(g) of at least 30° C.(such as those described in U.S. Pat. No. 6,797,387, assigned to PPGIndustries, Inc. and incorporated herein by reference).

After deposition of the powder coating composition, the coating is oftenheated to cure the deposited composition. The heating or curingoperation is often carried out at a temperature in the range of from150° C. to 200° C., such as from 170° C. to 190° C., for a period oftime ranging from 10 to 20 minutes. According to the invention, thethickness of the resultant film is from 50 microns to 125 microns.

As mentioned above, according to the present invention, the coatingcomposition may be a liquid coating composition. As used herein, “liquidcoating composition” refers to a coating composition which contains aportion of water and/or solvent. Accordingly, the liquid coatingcomposition disclosed herein is synonymous to waterborne and/orsolventborne coating compositions known in the art.

According to the present invention, the liquid coating composition maycomprise, for example, (a) a film forming polymer having a reactivefunctional group; and (b) a curing agent that is reactive with thefunctional group. In other examples, the liquid coating may contain afilm forming polymer that may react with oxygen in the air or coalesceinto a film with the evaporation of water and/or solvents. These filmforming mechanisms may require or be accelerated by the application ofheat or some type of radiation such as Ultraviolet or Infrared. Examplesof liquid coating compositions that may be used in the present inventioninclude the SPECTRACRON® line of solvent based coating compositions, theAQUACRON® line of waterbased coating compositions, and the RAYCRON® lineof UV cured coatings (all commercially available from PPG Industries,Inc.).

Suitable film forming polymers that may be used in the liquid coatingcomposition of the present invention may comprise a (poly)ester, analkyd, a (poly)urethane, an isocyanurate, a (poly)urea, a (poly)epoxy,an anhydride, an acrylic, a (poly)ether, a (poly)sulfide, a (poly)amine,a (poly)amide, (poly)vinyl chloride, (poly)olefin, (poly)vinylidenefluoride, (poly)siloxane, or combinations thereof.

According to the present invention, the substrate that has beencontacted with the sealing composition may also be contacted with aprimer composition and/or a topcoat composition. The primer coat may be,for examples, chromate-based primers and advanced performance topcoats.According to the present invention, the primer coat can be aconventional chromate based primer coat, such as those available fromPPG Industries, Inc. (product code 44GN072), or a chrome-free primersuch as those available from PPG (DESOPRIME CA7502, DESOPRIME CA7521,Deft 02GN083, Deft 02GN084). Alternately, the primer coat can be achromate-free primer coat, such as the coating compositions described inU.S. patent application Ser. No. 10/758,973, titled “CORROSION RESISTANTCOATINGS CONTAINING CARBON”, and U.S. patent application Ser. Nos.10/758,972, and 10/758,972, both titled “CORROSION RESISTANT COATINGS”,all of which are incorporated herein by reference, and other chrome-freeprimers that are known in the art, and which can pass the militaryrequirement of MIL-PRF-85582 Class N or MIL-PRF-23377 Class N may alsobe used with the current invention.

As mentioned above, the substrate of the present invention also maycomprise a topcoat. As used herein, the term “topcoat” refers to amixture of binder(s) which can be an organic or inorganic based polymeror a blend of polymers, typically at least one pigment, can optionallycontain at least one solvent or mixture of solvents, and can optionallycontain at least one curing agent. A topcoat is typically the coatinglayer in a single or multi-layer coating system whose outer surface isexposed to the atmosphere or environment, and its inner surface is incontact with another coating layer or polymeric substrate. Examples ofsuitable topcoats include those conforming to MIL-PRF-85285D, such asthose available from PPG (Deft 03W127A and Deft 03GY292). According tothe present invention, the topcoat may be an advanced performancetopcoat, such as those available from PPG (Defthane® ELT™ 99GY001 and99W009). However, other topcoats and advanced performance topcoats canbe used in the present invention as will be understood by those of skillin the art with reference to this disclosure.

According to the present invention, the metal substrate also maycomprise a self-priming topcoat, or an enhanced self-priming topcoat.The term “self-priming topcoat”, also referred to as a “direct tosubstrate” or “direct to metal” coating, refers to a mixture of abinder(s), which can be an organic or inorganic based polymer or blendof polymers, typically at least one pigment, can optionally contain atleast one solvent or mixture of solvents, and can optionally contain atleast one curing agent. The term “enhanced self-priming topcoat”, alsoreferred to as an “enhanced direct to substrate coating” refers to amixture of functionalized fluorinated binders, such as afluoroethylene-alkyl vinyl ether in whole or in part with otherbinder(s), which can be an organic or inorganic based polymer or blendof polymers, typically at least one pigment, can optionally contain atleast one solvent or mixture of solvents, and can optionally contain atleast one curing agent. Examples of self-priming topcoats include thosethat conform to TT-P-2756A. Examples of self-priming topcoats includethose available from PPG (03W169 and 03GY369), and examples of enhancedself-priming topcoats include Defthane® ELT™/ESPT and product codenumber 97GY121, available from PPG. However, other self-priming topcoatsand enhanced self-priming topcoats can be used in the coating systemaccording to the present invention as will be understood by those ofskill in the art with reference to this disclosure.

According to the present invention, the self-priming topcoat andenhanced self-priming topcoat may be applied directly to the sealedsubstrate. The self-priming topcoat and enhanced self-priming topcoatcan optionally be applied to an organic or inorganic polymeric coating,such as a primer or paint film. The self-priming topcoat layer andenhanced self-priming topcoat is typically the coating layer in a singleor multi-layer coating system where the outer surface of the coating isexposed to the atmosphere or environment, and the inner surface of thecoating is typically in contact with the substrate or optional polymercoating or primer.

According to the present invention, the topcoat, self-priming topcoat,and enhanced self-priming topcoat can be applied to the sealedsubstrate, in either a wet or “not fully cured” condition that dries orcures over time, that is, solvent evaporates and/or there is a chemicalreaction. The coatings can dry or cure either naturally or byaccelerated means for example, an ultraviolet light cured system to forma film or “cured” paint. The coatings can also be applied in a semi orfully cured state, such as an adhesive.

In addition, a colorant and, if desired, various additives such assurfactants, wetting agents or catalyst can be included in the coatingcomposition (electrodepositable, powder, or liquid). As used herein, theterm “colorant” means any substance that imparts color and/or otheropacity and/or other visual effect to the composition. Example colorantsinclude pigments, dyes and tints, such as those used in the paintindustry and/or listed in the Dry Color Manufacturers Association(DCMA), as well as special effect compositions.

In general, the colorant can be present in the coating composition inany amount sufficient to impart the desired visual and/or color effect.The colorant may comprise from 1 to 65 weight percent, such as from 3 to40 weight percent or 5 to 35 weight percent, with weight percent basedon the total weight of the composition.

For purposes of the following detailed description, it is to beunderstood that the invention may assume various alternative variationsand step sequences, except where expressly specified to the contrary.Moreover, other than in any operating examples, or where otherwiseindicated, all numbers such as those expressing values, amounts,percentages, ranges, subranges and fractions may be read as if prefacedby the word “about,” even if the term does not expressly appear.Accordingly, unless indicated to the contrary, the numerical parametersset forth in the following specification and attached claims areapproximations that may vary depending upon the desired properties to beobtained by the present invention. At the very least, and not as anattempt to limit the application of the doctrine of equivalents to thescope of the claims, each numerical parameter should at least beconstrued in light of the number of reported significant digits and byapplying ordinary rounding techniques. Where a closed or open-endednumerical range is described herein, all numbers, values, amounts,percentages, subranges and fractions within or encompassed by thenumerical range are to be considered as being specifically included inand belonging to the original disclosure of this application as if thesenumbers, values, amounts, percentages, subranges and fractions had beenexplicitly written out in their entirety.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard variation found in theirrespective testing measurements.

As used herein, unless indicated otherwise, a plural term can encompassits singular counterpart and vice versa, unless indicated otherwise. Forexample, although reference is made herein to “a” first composition, “a”second composition, and “an” oxidizing agent, a combination (i.e., aplurality) of these components can be used. In addition, in thisapplication, the use of “or” means “and/or” unless specifically statedotherwise, even though “and/or” may be explicitly used in certaininstances.

As used herein, “including,” “containing” and like terms are understoodin the context of this application to be synonymous with “comprising”and are therefore open-ended and do not exclude the presence ofadditional undescribed and/or unrecited elements, materials, ingredientsand/or method steps. As used herein, “consisting of” is understood inthe context of this application to exclude the presence of anyunspecified element, ingredient and/or method step. As used herein,“consisting essentially of” is understood in the context of thisapplication to include the specified elements, materials, ingredientsand/or method steps “and those that do not materially affect the basicand novel characteristic(s)” of what is being described.

Unless otherwise disclosed herein, the term “substantially free,” whenused with respect to the absence of a particular material, means thatsuch material, if present at all in a composition, a bath containing thecomposition, and/or layers formed from and comprising the composition,only is present in a trace amount of 5 ppm or less based on a totalweight of the composition or layer(s), as the case may be, excluding anyamount of such material that may be present or derived as a result ofdrag-in, substrate(s), and/or dissolution of equipment). Unlessotherwise disclosed herein, the term “essentially free,” when used withrespect to the absence of a particular material, means that suchmaterial, if present at all in a composition, a bath containing thecomposition, and/or layers formed from and comprising the composition,only is present in a trace amount of 1 ppm or less based on a totalweight of the composition or layer(s), as the case may be. Unlessotherwise disclosed herein, the term “completely free,” when used withrespect to the absence of a particular material, means that suchmaterial, if present at all in a composition, a bath containing thecomposition, and/or layers formed from and comprising the composition,is absent from the composition, the bath containing the composition,and/or layers formed from and comprising same (i.e., the composition,bath containing the composition, and/or layers formed from andcomprising the composition contain 0 ppm of such material).

As used herein, the terms “on,” “onto,” “applied on,” “applied onto,”“formed on,” “deposited on,” “deposited onto,” mean formed, overlaid,deposited, and/or provided on but not necessarily in contact with thesurface. For example, a coating layer “formed over” a substrate does notpreclude the presence of one or more other intervening coating layers ofthe same or different composition located between the formed coatinglayer and the substrate.

As used herein, a “salt” refers to an ionic compound made up of metalcations and non-metallic anions and having an overall electrical chargeof zero. Salts may be hydrated or anhydrous.

As used herein, “aqueous composition” refers to solution or dispersionin a medium that comprises predominantly water. For example, the aqueousmedium may comprise water in an amount of more than 50 wt. %, or morethan 70 wt. % or more than 80 wt. % or more than 90 wt. % or more than95 wt. %, based on the total weight of the medium. The aqueous mediummay for example consist substantially of water.

As used herein, “conversion composition” refers to a composition that iscapable of reacting with and chemically altering the substrate surfaceand binding to it to form a film that affords corrosion protection.

As used herein, “conversion bath” refers to an aqueous bath containingthe conversion composition and that may contain components that arebyproducts of the process of contacting a substrate with the conversioncomposition.

As used herein, the term “first composition metal cation(s)” refers tometal cations of a lanthanide series element, a Group IIA metal, a GroupIIIB metal, a Group IVB metal, a Group VB metal, a Group VIB metal, aGroup VIM metal, and/or a Group XII metal.

As used herein, a “sealing composition” refers to a composition, e.g. asolution or dispersion, that affects a substrate surface or a materialdeposited onto a substrate surface in such a way as to alter thephysical and/or chemical properties of the substrate surface (i.e., thecomposition affords corrosion protection).

As used herein, the term “Group IA metal” refers to an element that isin Group IA of the CAS version of the Periodic Table of the Elements asis shown, for example, in the Handbook of Chemistry and Physics, 63^(rd)edition (1983), corresponding to Group 1 in the actual IUPAC numbering.

As used herein, the term “Group IA metal compound” refers to compoundsthat include at least one element that is in Group IA of the CAS versionof the Periodic Table of the Elements.

As used herein, the term “Group IIIB metal” refers to yttrium andscandium of the CAS version of the Periodic Table of the Elements as isshown, for example, in the Handbook of Chemistry and Physics, 63^(rd)edition (1983), corresponding to Group 3 in the actual IUPAC numbering.For clarity, “Group IIIB metal” expressly excludes lanthanide serieselements.

As used herein, the term “Group IIIB metal compound” refers to compoundsthat include at least one element that is in group IIIB of the CASversion of the Periodic Table of the Elements as defined above.

As used herein, the term “Group IVB metal” refers to an element that isin group IVB of the CAS version of the Periodic Table of the Elements asis shown, for example, in the Handbook of Chemistry and Physics, 63^(rd)edition (1983), corresponding to Group 4 in the actual IUPAC numbering.

As used herein, the term “Group IVB metal compound” refers to compoundsthat include at least one element that is in Group IVB of the CASversion of the Periodic Table of the Elements.

As used herein, the term “Group VB metal” refers to an element that isin group VB of the CAS version of the Periodic Table of the Elements asis shown, for example, in the Handbook of Chemistry and Physics, 63^(rd)edition (1983), corresponding to Group 5 in the actual IUPAC numbering.

As used herein, the term “Group VB metal compound” refers to compoundsthat include at least one element that is in Group VB of the CAS versionof the Periodic Table of the Elements.

As used herein, the term “Group VIB metal” refers to an element that isin group VIB of the CAS version of the Periodic Table of the Elements asis shown, for example, in the Handbook of Chemistry and Physics, 63^(rd)edition (1983), corresponding to Group 6 in the actual IUPAC numbering.

As used herein, the term “Group VIB metal compound” refers to compoundsthat include at least one element that is in Group VIB of the CASversion of the Periodic Table of the Elements.

As used herein, the term “lanthanide series elements” refers to elements57-71 of the CAS version of the Periodic Table of the Elements andincludes elemental versions of the lanthanide series elements. Inembodiments, the lanthanide series elements may be those which have bothcommon oxidation states of +3 and +4, referred to hereinafter as +3/+4oxidation states.

As used herein, the term “lanthanide compound” refers to compounds thatinclude at least one of elements 57-71 of the CAS version of thePeriodic Table of the Elements.

As used herein, the term “halogen” refers to any of the elementsfluorine, chlorine, bromine, iodine, and astatine of the CAS version ofthe Periodic Table of the Elements, corresponding to Group VIIA of theperiodic table.

As used herein, the term “halide” refers to compounds that include atleast one halogen.

As used herein, the term “aluminum,” when used in reference to asubstrate, refers to substrates made of or comprising aluminum and/oraluminum alloy, and clad aluminum substrates.

As used herein, the term “oxidizing agent,” when used with respect to acomponent of the conversion composition, refers to a chemical which iscapable of oxidizing at least one of: a metal present in the substratewhich is contacted by the conversion composition, a lanthanide serieselement present in the conversion composition, and/or a metal-complexingagent present in the conversion composition. As used herein with respectto “oxidizing agent,” the phrase “capable of oxidizing” means capable ofremoving electrons from an atom or a molecule present in the substrateor the conversion composition, as the case may be, thereby decreasingthe number of electrons of such atom or molecule.

Unless otherwise disclosed herein, as used herein, the terms “totalcomposition weight”, “total weight of a composition” or similar termsrefer to the total weight of all ingredients being present in therespective composition including any carriers and solvents.

In view of the foregoing description the present invention thus relatesin particular, without being limited thereto, to the following Aspects1-29:

Aspects

1. A system for treating a substrate comprising: a first composition forcontacting at least a portion of the substrate, the first compositioncomprising a lanthanide series element cation and an oxidizing agent

2. The system of Aspect 1, wherein the oxidizing agent is present in thefirst composition in an amount of 25 ppm to 25,000 ppm based on totalweight of the first composition.

3. The system of Aspect 1 or 2, wherein the lanthanide series elementcation comprises cerium, praseodymium, or combinations thereof.

4. The system of any of the preceding Aspects, wherein the lanthanideseries element cation is present in the first composition in an amountof 50 ppm to 200 ppm (calculated as cation) based on total weight of thefirst conversion composition.

5. The system of any of the preceding Aspects, further comprising asecond composition for treating at least a portion of the substrate, thesecond composition comprising a Group IA metal cation.

6. The system of Aspect 5, wherein the Group IA metal cation compriseslithium, sodium, potassium, or combinations thereof.

7. The system of Aspect 5 or 6, wherein the Group IA metal cation ispresent in the second composition in an amount of 5 ppm to 30,000 ppm(as metal cation) based on a total weight of the second composition.

8. The system of any of Aspects 5 to 7, wherein the second compositionhas a pH of 8 to 13.

9. The system of any of Aspects 1 to 4, further comprising a thirdcomposition for treating at least a portion of the substrate, the secondcomposition comprising a Group IVB metal cation.

10. The system of Aspect 9, wherein the Group IVB metal cation compriseszirconium, titanium, or combinations thereof.

11. The system of Aspect 9 or 10, wherein the Group IVB metal cation ispresent in the third composition in an amount of 110 ppm to 170 ppm (asmetal cation) based on a total weight of the third composition.

12. The system of any of Aspects 9 to 11, wherein the third compositionhas a pH of 4 to 5.

13. The system of any of Aspects 9-12, wherein the third compositionfurther comprises an amino compound.

14. The system of any of the preceding Aspects, wherein the system issubstantially free of phosphate.

15. A substrate treated with the system of any of the preceding Aspects.

16. The substrate of Aspect 15, wherein the substrate treated with thesystem has at least a 5% decrease in scribe creep on the substratesurface compared to a substrate treated with a composition comprisingzirconium as measured by CASS testing.

17. The substrate of Aspect 15 or Aspect 16, wherein at least a portionof the substrate surface is sanded, and wherein the substrate treatedwith the system has at least a 55% decrease in scribe creep on thesanded substrate surface compared to a sanded substrate treated with acomposition comprising zirconium as measured by filiform corrosiontesting.

18. The substrate of any of Aspect 15 to 17, wherein at least a portionof the substrate surface is sanded, and wherein the substrate treatedwith the system has at least a 78% decrease in scribe creep on thesanded substrate surface compared to a sanded substrate treated with acomposition comprising zirconium as measured by ASTM G85 A2 corrosiontesting.

19. A substrate treated with the system of Aspect 5.

20. The substrate of Aspect 19, wherein the substrate treated with thesystem has at least a 25% decrease in scribe creep on the substratesurface compared to a substrate treated with a composition comprisingzirconium as measured by ASTM G85 A2 testing.

21. The substrate treated with the system of Aspect 9.

22. The substrate of Aspect 21, wherein the substrate treated with thesystem has at least one of the following: a 13% decrease in scribe creepon the substrate surface compared to a substrate treated with acomposition comprising a lanthanide series element cation or a Group IVBmetal cation but not both as measured by CASS testing; a 47% decrease inscribe creep on the substrate surface compared to a substrate treatedwith a composition comprising a lanthanide series element cation or aGroup IVB metal cation but not both as measured by SAE J2635; and/or atleast a 42% increase in crosshatch adhesion compared to a substratetreated with a composition comprising a lanthanide series element cationor a Group IVB metal cation but not both.

23. A method of treating a substrate comprising: contacting at least aportion of the substrate surface with a first composition comprising alanthanide series element cation and an oxidizing agent.

24. The method of Aspect 23, wherein the substrate surface is contactedwith the first composition to result in a level of the lanthanide serieselement cation on the contacted substrate surface of at least 100 countsgreater than on a surface of a substrate that is not contacted with thefirst composition as measured by X-ray fluorescence (measured usingX-Met 7500, Oxford Instruments; operating parameters 60 second timedassay, 15Kv, 45 μA, filter 3, T(p)=1.5 μs).

25. The method of Aspect 23 or 24, further comprising contacting atleast a portion of the substrate surface with a second compositioncomprising a Group IA metal cation and/or a Group IVB metal cation.

26. The method of any of Aspects 23 to 25, wherein the contacting withthe first composition occurs prior to the contacting with the secondcomposition.

27. The method of any of Aspects 23 to 25, wherein the contacting withthe second composition occurs prior to the contacting with the firstcomposition.

28. The method of any of Aspects 23 to 27, wherein the contacting withthe first composition is 15 seconds to 4 minutes.

29. The method of any of Aspects 23 to 28, further comprising heatingthe substrate for 15 minutes to 30 minutes at a temperature of 110° C.to 232° C.

30. A substrate treated according to the method of Aspect 29, whereinthe substrate has a b* value of less than 3.09 (spectral componentexcluded, 25 mm aperture).

Whereas particular features of the present invention have been describedabove for purposes of illustration, it will be evident to those skilledin the art that numerous variations of the details of the coatingcomposition, coating, and methods disclosed herein may be made withoutdeparting from the scope in the appended claims.

Illustrating the invention are the following examples that are not to beconsidered as limiting the invention to their details. All parts andpercentages in the examples, as well as throughout the specification,are by weight unless otherwise indicated.

EXAMPLES Example 1 Cleaner Bath

A cleaner bath was prepared at 1.25% v/v concentration of Chemkleen2010LP (a phosphate-free alkaline cleaner available from PPG) and 0.125%of Chemkleen 181 ALP (a phosphate-free blended surfactant additive,available from PPG). For spray cleaning, a 10 gallon bath was prepared.The bath was made up with deionized water. The temperature of the bathwas 120° F. and when panels were run through the cleaner it was utilizedfor 2 minutes. The pressure of the spray cleaning was that of 10-15 psiwith the utilization of a series of “vee jet” spray nozzles.

Zinc Phosphate Pretreatment Bath 1 (Comparative)

A five gallon vessel was filled approximately three-fourths full withdeionized water. To this was added 700 ml of Chemfos 700A, 1.5 mlChemfos FE, 51 ml Chemfos AFL, and 375m₁s of Chemfos 700B (all availablefrom PPG). To this was added 28.6 g zinc nitrate hexahydrate and 2.5grams of Sodium Nitrite (both available from Fischer Scientific). Thefree acid of the bath was operated at 0.7-0.8 points of free acid, 15-19points of total acid, and 2.2-2.7 gas points of nitrite. Free acid andtotal acid were measured as follows:

Equipment:

-   -   Reeve Angel 802 filter paper or equivalent    -   10 ml pipette    -   Analytical funnel    -   25-50 ml burette    -   150 ml beakers

Reagents:

-   -   0.1 N Sodium Hydroxide    -   Bromophenol Blue Indicator    -   Phenolphthalein Indicator

Procedure for Free Acid Titration:

-   -   1. A sample of the phosphating bath was filtered.    -   2. 10 mls of filtered solution were pipetted into a clean, dry        150 ml beaker.    -   3. 3-5 drops of bromophenol blue indicator were added to the        beaker containing the filtered solution    -   4. The solution was titrated with 0.1 N sodium hydroxide        solution from yellow-green to a clear, light blue, absence of        green but before blue-violet, end point.    -   5. The number of mls 0.1 N sodium hydroxide used was recorded as        the Free Acid.

Procedure for Total Acid Titration:

-   -   1. A sample of the phosphating bath was filtered.    -   2. 10 mis of filtered solution were pipetted into a clean, dry        150 ml beaker.    -   3. 3-5 drops of Phenolphthalein indicator were added to the        beaker containing the filtered solution    -   4. The solution was titrated with 0.1 N sodium hydroxide        solution until a permanent pink color appeared.    -   5. The number of mis 0.1 N sodium hydroxide used was recorded as        the Total Acid.

The amount of nitrite in solution was measured using a fermentation tubeusing the protocol described in the technical data sheet for ChemfosLiquid Additive (PPG Industries, Inc., Cleveland, Ohio). A fermentationtube was filled with a 70 mL sample of the pretreatment bath to justbelow the mouth of the tube. Approximately 2.0 g of sulfamic acid wasadded to the tube, and the tube was inverted to mix the sulfamic acidand pretreatment solution. Gas evolution occurred, which displaced theliquid in the top of the fermentation tube, and the level was read andrecorded. The level corresponded to the gas points measured in thesolution in milliliters.

To adjust to obtain the correct amounts of free and total acid, CF700 Bwas utilized to adjust according to product data sheet. The temperatureof the bath was 125° F. and when panels were run through the bath it wasutilized for 2 minutes.

Rinse Conditioner Bath

1.1 g/L of Versabond RC (also known as RC30, commercially available fromPPG Industries, Inc.) was added to a filled 5 gallon (18.79 liters)vessel of deionized water to be utilized immediately prior to the use ofthe zinc phosphate bath described above. The temperature of the bath was80° F. and when panels were run through the bath it was utilized for 1minute.

Zirconium-Containing Pretreatment Bath 2 (Comparative)

Zircobond 1.5 (a zirconium-containing pretreatment compositioncommercially available from PPG Industries, Inc.) was added to 5 gallonsof deionized water according to manufacturer's instructions to yield acomposition containing 175 ppm of zirconium.

The resultant solution had a pH of 4.72, measured using a ThermoScientific Orion Dual Star pH/ISE Bench Top Reader attached to anAccumet Cat #13-620-221 pH probe. The temperature of the bath was 80° F.and when panels were run through the bath it was utilized for 2 minutes.

Zirconium-Containing Pretreatment Bath 3 (Comparative)

Zircobond 2.0 (a zirconium-containing pretreatment compositioncommercially available from PPG Industries, Inc.) was added to 5 gallonsof deionized water according to manufacturer's instructions to yield acomposition containing 175 ppm of zirconium, 5 ppm lithium, and 40 ppmMo.

The resultant solution had a pH of 4.72. The temperature of the bath was80° F. and when panels were run through the bath it was utilized for 2minutes.

Cerium-Containing Pretreatment Bath 4 (Experimental)

To a 2 liter vessel of deionized water was added 3 Grams Cerium (III)Chloride Heptahydrate (Available from Acros Organics) and 5 Grams 29-32%Hydrogen Peroxide (Available from Alfa Aesar). The temperature of thebath was ambient, and the bath was still when the panel was immersed(i.e., not stirred or agitated). When the panels were run through thebath it was utilized for 2 minutes.

Test Panel Preparation

Aluminum Panel Preparation: X610 (ACT Test Panels LLC, Hillsdale, Mich.)were cut in half to make panel size 4″×6″. The bottom 3 inches of eachpanel was sanded with P320 grit paper available from 3M which wasutilized on a 6″ random orbital palm sander available from ATD (AdvancedTool Design Model-ATD-2088). The sanding was utilized to help determineany corrosion performance that may have been on sanded and unsandedparts of the metal. Sanding is used in the field as a means to increasethe adhesion of subsequent paint surfaces.

For each run, two half sanded X610 Aluminum panels (cut to 4″×6″ fromACT Test Panels, LLC) were first cleaned as follows: All testing panelswere spray cleaned in a stainless steel spray cabinet using Vee-jetnozzles at 10 to 15 psi, using the standard Chemkleen 2010LP/181ALP bathdetailed above for two minutes at 49° C., followed by immersion rinse inDI water for 15 seconds and spray rinse with DI water for 15 seconds.

Panels were then introduced into one of the pretreatment baths describedabove as follows:

Set 1—Panels were immersed in the Rinse Conditioner Bath 1 minute andthen immediately were immersed in Pretreatment Bath 1 for 2 minutes.

Set 2—Panels were immersed in Pretreatment Bath 2 for 2 minutes.

Set 3—Panels were immersed in Pretreatment Bath 3 for 2 minutes.

Set 4—Panels were immersed in Pretreatment Bath 4 for 2 minutes.

Following immersion in one of the Pretreatment Baths, all panels thenwere spray rinsed with DI water for 20-30 seconds. Panels were warm airdried using a Hi-Velocity handheld blow-dryer made by Oster® (modelnumber 078302-300-000) on high-setting at a temperature of about 50-55°C. until the panel was dry (about 1-5 minutes).

After drying, the panels were electrocoated with ED7000Z electrocoat,available from PPG. The electrocoat was applied to target a 0.60 milthickness. The rectifier (Xantrex Model XFR600-2) was set to the“Coulomb Controlled” setting. The conditions were set with 23 coulombsfor Zinc Phosphate and 24 Coulombs for Zirconium and Experimental CeChloride Pretreatment, 0.5 amp limit, voltage set point of 220 V forZinc Phosphate and 180V for Zirconium and Experimental Ce ChloridePretreatment, and a ramp time of 30s. The electrocoat was maintained at90° F., with a stir speed of 340 rpms. After the electrocoat wasapplied, the panels were baked in an oven (Despatch Model LFD-1-42) at177° C. for 25 minutes. The coating thickness was measured using a filmthickness gauge (Fischer Technology Inc. Model FMP40C).

Panels were evaluated for a yellowing of the electrocoat layer by visualinspection by the naked eye. Panels also were tested for scribe creepblistering using the ASTM-B 368-09 Copper Acetic Acid Salt Spray, tomeasure scribe creep. Scribe creep was measured from affected paint toaffected paint to the left and right of the scribe. The scribe wasplaced into the panel prior to being placed into the cabinet for alength of 20 Days or 480 Hours.

The scribe was measured according to the following protocol: the scribelength was 4 Inches/10.16 cm. A reading of affected paint to affectedpaint was measured at each cm along the scribe creating a total of 10points of measurement. From this the average of the two panels led toaverage scribe creep reported in Table 1 below. The measurements weremade by the use of a Fowler Sylvac digital caliper Model S 235.

The table below provides Scribe Creep Measurements from the panelstested as described above.

TABLE 1 Average Scribe Creep (mm) and Color of Electrocoat AverageYellowing Pretreatment Scribe Creep after Electrocoat Pretreatment Bath3.52 mm (65%) No 1 (Comparative) Pretreatment Bath 1.70 mm (27%) Yes 2(Comparative) Pretreatment Bath 1.31 mm (5%) Yes 3 (Comparative)Pretreatment Bath 1.24 mm No 4 (Experimental)

The data in Table 1 demonstrate that an electrocoated panel pretreatedwith a pretreatment composition comprising cerium results in a 5%reduction in the scribe creep following 480 hours exposure to copperacetic salt spray (ASTM-B 368-09) compared to an electrocoated panelpretreated with a zirconium/molybdenum/lithium-containing pretreatment.Notably, an electrocoated panel treated with a zirconium-containingpretreatment composition is visibly yellow to the naked eye, while anelectrocoated panel treated with a lanthanide-containing pretreatmentcomposition is not visibly yellow to the naked eye.

The data in Table 1 also demonstrate that an electrocoated panelpretreated with a pretreatment composition comprising cerium results ina 27% reduction in the scribe creep following 480 hours exposure tocopper acetic salt spray (ASTM-B 368-09) compared to an electrocoatedpanel pretreated with a zirconium-containing pretreatment.

The data shown in Table 1 also demonstrate that an electrocoated panelpretreated with a pretreatment composition comprising cerium results ina 65% reduction in the scribe creep following 480 hours exposure tocopper acetic salt spray (ASTM-B 368-09) compared to an electrocoatedpanel pretreated with a zinc phosphate pretreatment.

Example 2 Example #2A

Aluminum 6111 panels (from ACT Test Panels, LLC) were cut to 4″×6″sample size. The bottom 3″ of the panels were sanded with P320 gritsilicon carbide paper (available from 3M) on a 6″ random orbital palmsander (Advanced Tool Design Model-ATD-2088). Half-sanding the panelsurface served to determine any corrosion performance difference betweenas-milled (unsanded) and sanded substrates. Surface sanding or abrasionis conducted in the field to promote adhesion of subsequent paintapplications.

Each of the half-sanded 6111 aluminum panels were spray cleaned withstandard Chemkleen 2010LP/181ALP bath (composed of 1.25 vol. % ofChemkleen 2010LP (a phosphate-free alkaline cleaner available from PPGIndustries, Inc.) and 0.125 vol. % of Chemkleen 181 ALP (aphosphate-free blended surfactant additive, available from PPGIndustries, Inc.) in deionized water) in a stainless steel spray tankusing vee-jet nozzles at 10 to 15 psi, for two minutes at 120° F. Thiswas followed by immersion rinse in DI water for 15 seconds, and finalspray rinse with DI water for 15 seconds.

Immediately after spray rinsing, the cleaned panels were introduced tothe pretreatment baths.

The first set of panels were pretreated with Zircobond 1.5, azirconium-containing pretreatment composition commercially availablefrom PPG Industries, Inc. A 5-gallon bath was prepared as permanufacturer's instruction to yield a pH of 4.72, a zirconiumconcentration of 200 ppm, and a free fluoride concentration of 101 ppm.The panels were pretreated by immersion into the pretreatment bath at80° F. with low agitation, for 2 minutes.

The second set of panels were pretreated with a cerium chloridepretreatment composition. The cerium chloride pretreatment bath wascomposed of 0.15 wt. % of cerium (III) chloride heptahydrate (availablefrom Acros Organics) and 0.25 wt. % of a 29 to 32% solution of hydrogenperoxide (available from Alfa Aesar) in deionized water. The panels werepretreated by immersion into a 3 gallon pretreatment bath at ambienttemperature without any agitation for 2 minutes.

Upon removal from the pretreatment baths, the pretreated panels werespray rinsed with DI water for 20 to 30 seconds. Panels were air driedusing a Hi-Velocity handheld blow-dryer made by Oster® (model number078302-300-000) on high-setting at a temperature of about 50-55° C.until fully dry (about 3 to 5 minutes).

The pretreated panels were electrocoated with cationic ED6280Z paint(available from PPG) using a direct current rectifier (Xantrex ModelXFR600-2). A coating dry film thickness of 0.8 mil was achieved bypassing a 24.5 C or 20.0 C charge for the zirconium and ceriumpretreatments, respectively, at a current limit of 0.5 A, and an appliedelectrical potential of 220 V after a 30 second ramp time. The ED6280Zpaint bath was maintained at 90° F. with a stir rate of 340 rpm. Theelectrocoated panels were spray rinsed with DI water. The panels werebaked in an electric oven (Despatch Model LFD-1-42) at 177° C. for 25minutes. The coating thickness was measured using a Permascope (FischerTechnology Inc. Model FMP40C).

Two corrosion test methods were utilized to evaluate the corrosionperformance of the panels: ASTM G85 A2 Cyclic Acidified Salt Fog Testingfor 3 weeks, and a filiform corrosion for 6 weeks. For the latter test,the panels were placed horizontally in a desicator containing a thinlayer of 12 N hydrochloric acid (HCl) for 1 hour at ambient temperature,such that only the HCl fumes came into contact with the sample, within 5minutes, the panels were placed in a vertical orientation in thehumidity cabinet maintained at 40 C and 80% relative humidity for 6weeks. Duplicate panels were included for each testing. Prior tocorrosion testing, the panels were scribed with an X-configuration. Thescribe was positioned with the top legs on the as-milled surface and thebottom legs on the sanded surface. Each leg is 40 mm long.

Corrosion damage is measured as the perpendicular distance from thescribe to tip of the filament or blister. Each panel provided two setsof five measurements: a set from the top legs for the as-milled surface,and another set from the bottom legs for the sanded surface.Measurements were taken from the five longest corrosion sites. Theaverage corrosion damage was calculated based on a total of tenmeasurements from duplicate panels. All readings were measured using aFowler Sylvac digital caliper Model S 235.

The average corrosion damage is reported in Table 1.1 below. Relative tothe control zirconium pretreatment, the cerium chloride pretreatedpanels displayed better corrosion performance on sanded and unsanded6111 aluminum alloys.

TABLE 1.1 Average corrosion damage Average Corrosion Damage (mm)As-milled (unsanded) Sanded Zirconium Cerium Zirconium Cerium TestMethod (control) Chloride (control) Chloride Filiform 4.93 2.56 12.535.61 Corrosion Test ASTM G85 A2 2.76 1.08 10.39 2.21

Example #2B

Aluminum 6111 panels (from ACT Test Panels, LLC) were cut to 4″×6″sample size. The bottom 3″ of the panels were sanded with P320 gritsilicon carbide paper (available from 3M) on a 6″ random orbital palmsander (Advanced Tool Design Model-ATD-2088). Half-sanding the panelsurface served to determine any corrosion performance difference betweenas-milled (unsanded) and sanded substrates. Surface sanding or abrasionis conducted in the field to promote adhesion of subsequent paintapplications.

Each of the half-sanded 6111 aluminum panels were spray cleaned withstandard Chemkleen 2010LP/181ALP bath (composed of 1.25 vol. % ofChemkleen 2010LP (a phosphate-free alkaline cleaner available from PPGIndustries, Inc.) and 0.125 vol. % of Chemkleen 181 ALP (aphosphate-free blended surfactant additive, available from PPGIndustries, Inc.) in deionized water in a stainless steel spray tankusing vee-jet nozzles at 10 to 15 psi, for two minutes at 120° F. Thiswas followed by immersion rinse in DI water for 15 seconds, and finalspray rinse with DI water for 15 seconds.

Immediately after spray rinsing, the cleaned panels were introduced tothe pretreatment baths.

The first set of panels were pretreated with Zircobond 1.5, azirconium-containing pretreatment composition commercially availablefrom PPG Industries, Inc. A 5-gallon bath was prepared according tomanufacturer's instruction to yield a pH of 4.72, a zirconiumconcentration of 200 ppm, and a free fluoride concentration of 101 ppm.The panels were pretreated by immersion into the pretreatment bath at80° F. with low agitation, for 2 minutes. The panels were spray rinsedwith DI water for 20 to 30 seconds, and air dried using a Hi-Velocityhandheld blow-dryer made by Oster® (model number 078302-300-000) onhigh-setting at a temperature of about 50-55° C. until fully dry (about3 to 5 minutes).

The second through fifth sets of panels were pretreated with a two-steppretreatment process wherein the panel is pretreated with two separatepretreatment compositions prepared as three-gallon baths with thecompositions as described below.

The cerium chloride pretreatment bath was composed of 0.15 wt. % ofcerium (III) chloride heptahydrate (available from Acros Organics) and0.25 wt. % of hydrogen peroxide, 29 to 32% solution, (available fromAlfa Aesar) in deionized water.

The lithium hydroxide pretreatment bath was composed of 0.17 wt. % oflithium hydroxide monohydrate (available from Acros Organics) indeionized water.

The lithium carbonate pretreatment bath was composed of 0.15 wt. % oflithium carbonate (available from Acros Organics) in deionized water.

The second set of panels were treated with a cerium chloride/lithiumhydroxide two-step pretreatment process. The panels were firstpretreated by immersion into the cerium chloride pretreatmentcomposition at ambient temperature for 2 minutes, without agitation. Thepanels were spray rinsed with DI water, followed by full immersionpretreatment in the lithium hydroxide pretreatment composition for 1minute at ambient temperature. The panels were air dried using aHi-Velocity handheld blow-dryer made by Oster® (model number078302-300-000) on high-setting at a temperature of about 50-55° C.until fully dry (about 3 to 5 minutes).

The third set of panels were treated with a cerium chloride/lithiumcarbonate two-step pretreatment process. The panels were firstpretreated by immersion into the cerium chloride pretreatmentcomposition at ambient temperature for 2 minutes, without agitation. Thepanels were spray rinsed with DI water, followed by full immersionpretreatment in the lithium carbonate pretreatment for 1 minute atambient temperature. The panels were air dried using a Hi-Velocityhandheld blow-dryer made by Oster® (model number 078302-300-000) onhigh-setting at a temperature of about 50-55° C. until fully dry (about3 to 5 minutes).

The fourth set of panels were pretreated with a lithium hydroxide/ceriumchloride two-step pretreatment process. The panels were first pretreatedby immersion into the lithium hydroxide pretreatment composition atambient temperature for 1 minute, and directly followed by immersioninto the cerium chloride pretreatment composition for 2 minutes. Thepanels were spray rinsed with DI water for 20 to 30 seconds, and airdried using a Hi-Velocity handheld blow-dryer made by Oster® (modelnumber 078302-300-000) on high-setting at a temperature of about 50-55°C. until fully dry (about 3 to 5 minutes).

The fifth set of panels were pretreated with a lithium carbonate/ceriumchloride two-step pretreatment process. The panels were first pretreatedby immersion into the lithium carbonate pretreatment composition atambient temperature for 1 minute, and directly followed by immersioninto the cerium chloride pretreatment composition for 2 minutes. Thepanels were spray rinsed with DI water for 20 to 30 seconds, and airdried using a Hi-Velocity handheld blow-dryer made by Oster® (modelnumber 078302-300-000) on high-setting at a temperature of about 50-55°C. until fully dry (about 3 to 5 minutes).

TABLE 2.1 Summary of pretreatment schemes Set Pretreatment 1 RinsePretreatment 2 Rinse 1 Zirconium DI water N/A N/A (Control) (Zircobondspray 1.5) 2 Cerium DI water Lithium No rinse Chloride spray Hydroxide 3Cerium DI water Lithium No rinse Chloride spray Carbonate 4 Lithium Norinse Cerium DI water Hydroxide Chloride spray 5 Lithium No rinse CeriumDI water Carbonate Chloride spray

The pretreated panels were electrocoated with cationic ED6280Z paint(available from PPG) using a direct current rectifier (Xantrex ModelXFR600-2). A coating dry film thickness of 0.8 mil was achieved with thecoat out parameters listed in Table 2.2. The ED6280Z paint bath wasmaintained at 90° F., with a stir rate of 340 rpm. The electrocoatedpanels were spray rinsed with DI water. The panels were baked in anelectric oven (Despatch Model LFD-1-42) at 177° C. for 25 minutes. Thecoating thickness was measured using a Permascope (Fischer TechnologyInc. Model FMP40C).

TABLE 2.2 ED6280Z coat-out parameters Current Ramp Set PretreatmentCharge, C Potential, V Limit, A Time, s 1 Zirconium 24.5 220 0.5 30(Control) 2 Cerium 21.0 220 0.5 30 Chloride/ Lithium Hydroxide 3 Cerium21.0 220 0.5 30 Chloride/ Lithium Carbonate 4 Lithium 21.5 220 0.5 30Hydroxide/ Cerium Chloride 5 Lithium 20.5 220 0.5 30 Carbonate/ CeriumChloride

Two corrosion test methods were utilized to evaluate the corrosionperformance of the panels: ASTM G85 A2 Cyclic Acidified Salt Fog Testingfor 3 weeks, and a filiform corrosion for 6 weeks. For the latter test,the panels were placed horizontally in a desicator containing a thinlayer of 12 N hydrochloric acid (HCl) for 1 hour at ambient temperature,such that only the HCl fumes came into contact with the sample, within 5minutes, the panels were placed in a vertical orientation in thehumidity cabinet maintained at 40 C and 80% relative humidity for 6weeks. Duplicate panels were included for each testing. Prior tocorrosion testing, the panels were scribed with an X-configuration. Thescribe was positioned with the top legs on the as-milled surface and thebottom legs on the sanded surface. Each leg is 40 mm long.

Corrosion damage is measured as the perpendicular distance from thescribe to tip of the filament or blister. Each panel provided two setsof five measurements: a set from the top legs for the as-milled surface,and another set from the bottom legs for the sanded surface.Measurements were taken from the five longest corrosion sites. Theaverage corrosion damage was calculated based on a total of tenmeasurements from duplicate panels. All readings were measured using aFowler Sylvac digital caliper Model S 235.

The average corrosion damage is tabulated in Table 2.3. Relative to thecontrol Zirconium pretreatment, all the experimental two-steppretreatments displayed better corrosion performance on sanded 6111aluminum alloys.

TABLE 2.3 Average corrosion damage Average Corrosion Damage (mm)As-milled (Unsanded) Sanded Filiform Filiform Corrosion ASTM CorrosionASTM Pretreatment Test G85 A2 Test G85 A2 Zirconium 4.93 2.76 12.5310.39 (control) Cerium 5.02 1.86 6.47 3.22 Chloride/ Lithium HydroxideCerium 5.40 4.15 5.59 4.45 Chloride/ Lithium Carbonate Lithium 4.76 2.825.14 4.78 Hydroxide/ Cerium Chloride Lithium 5.08 2.04 6.25 4.87Carbonate/ Cerium Chloride

Example 3 Bath Preparation

Standard ChemKleen 2010LP/181ALP Cleaner: The cleaner bath was preparedat 1.25% v/v concentration of Chemkleen 2010LP (a phosphate-freealkaline cleaner available from PPG) and 0.125% of Chemkleen 181 ALP (aphosphate-free blended surfactant additive, available from PPG) indeionized water. For spray cleaning, a 10-gallon bath was prepared.Temperature of the bath was 120° F. and when panels were run through thecleaner it was utilized for 2 minutes. The pressure of the spraycleaning was 10 psi to 15 psi.

Control Zircobond 1.5 (ZB-1.5, commercially available zirconiumpretreatment composition): To 5 gallons of deionized water was added16.73 grams 45% hexafluorozirconic acid (available from HoneywellInternational Inc.), 30.02 grams of a 2% by weight copper solution(prepared by dissolving copper nitrate hemipentahydrate, available fromFisher Scientific, in deionized water), 15.4 grams of Chemfos AFL(available from PPG), and 29.8 grams of Chemfil Buffer (available fromPPG). The resultant solution had a pH of 4.68 and 103 ppm of freefluoride.

Cerium Chloride Pretreatment Composition: To a 2 liter vessel ofdeionized water was added 3 Grams Cerium (III) Chloride Heptahydrate(Available from Acros Organics) and 5 Grams 29-32% Hydrogen Peroxide(Available from Alfa Aesar).

Test Panel Preparation

Set A panels were Zinc Hot Dipped Galvanized Unexposed (70G70UHDG)substrates pretreated with Chemfos®700 Zinc Phosphate Pretreatment,purchased from ACT Test Panels (Item No. 40085).

Zinc Hot Dipped Galvanized Exposed (HD60G60E) Item No. 53170 from ACTTest Panels were cut in half to make panel size 4″×6″.

For each run, two Zinc Hot Dipped Galvanized Exposed (cut to 4″×6″ fromACT Test Panels, LLC) were first cleaned as follows: The panels werespray cleaned in a stainless-steel spray cabinet using the standardChemkleen 2010LP/181ALP bath described above for two minutes at a bathtemperature of 49° C. at 10-15 psi spray pressure using a series of “veejet” spray nozzles, followed by immersion rinse in DI water for 15seconds and spray rinse with DI water for 15 seconds.

The cleaned panels were then immersed into one of the two pretreatmentcompositions described above:

Set B: Panels were immersed in the Zircobond 1.5 (ZB-1.5) pretreatmentbath for 2 minutes at a bath temperature of 80° F.

Set C: Panels were immersed in the Cerium Chloride Pretreatment bath for1 minute at ambient temperature.

All panels from set B and C were then spray rinsed with DI water for20-30 seconds. Panels were warm air dried using a Hi-Velocity handheldblow-dryer made by Oster® (model number 078302-300-000) on high-settingat a temperature of about 50-55° C. until the panel was dry (about 1-5minutes).

All panels from Set A, B and C were electrocoated with ED7000Zelectrocoat, available from PPG. The electrocoat was applied to targetof 0.60 mil thickness. The rectifier (Xantrex Model XFR600-2) was set tothe “Coulomb Controlled” setting. The conditions were set with 23coulombs for Set A (zinc phosphate pretreatment) and 24 Coulombs for SetB (zirconium pretreatment) and Set C (cerium chloride pretreatment), 0.5amp limit, voltage set point of 220 V for Set A and 180V for Set B andSet C, and a ramp time of 30 seconds. The electrocoat was maintained at90° F., with a stir speed of 340 rpms. After the electrocoat wasapplied, the panels were baked in an oven (Despatch Model LFD-1-42) at177° C. for 25 minutes. The coating thickness was measured using a filmthickness gauge (Fischer Technology Inc. Model FMP40C).

The coated panels were tested for scribe creep blistering using the GMW14872 Cyclic Corrosion testing method. Scribe creep is measured fromaffected paint to affected paint to the left and right of the scribe.The scribe is placed into the panel prior to being placed into thecabinet for a length of 40 cycles.

Two testing panels were evaluated to obtain the average scribe creep.The length of scribe was 4 inches (10.16 cm). A reading of affectedpaint to affected paint was measured at each centimeter along the scribecreating a total of 10 points of measurement for each panel. Themeasurements were taken by the use of a Fowler Sylvac digital caliperModel S 235. The average scribe creep of each panel was the averagescribe creep for the 10 measurements. From this, the average of theaverage scribe creep of each of the two panels led to the average scribecreep for each set noted below in Table 3.1.

TABLE 3.1 Set (Pretreatment) Average Scribe Creep Set A (Zinc Phosphate)2.35 (21%) Set B (Zircobond 1.5) 4.29 (57%) Set C (Experimental 1.85Cerium Chloride)

The data in Table 3.1 demonstrate at least a 21% decrease in averagescribe creep on panels treated with the system of the present invention(i.e., cerium pretreatment composition) compared to panels treated witha zinc phosphate pretreatment composition or a zirconium pretreatmentcomposition as measured by GMW 14872 Cyclic Corrosion testing.

Example 4 Bath Compositions

Standard Ultrax 14AWS Cleaner: The bath was prepared at 1.25% v/vconcentration of Ultrax 14 (a mild alkaline cleaner blended withsurfactants available from PPG) in deionized water.

AMC66AW Deoxidizer: The bath was prepared with 2% v/v concentration ofAMC66 (an acidic deoxidizer free of nitric acid available from PPG).Panels were run through the bath at 120° F. for 1 min.

Control X-Bond (commercially available zirconium pretreatmentcomposition): To 5 gallons of deionized water was added 24.13 grams 45%hexafluorozirconic acid (available from Honeywell International Inc.),16 grams of Chemfos AFL (available from PPG), and 33 grams of ChemfilBuffer (available from PPG). The resultant solution had a pH of 4.63 and91.2 ppm of free fluoride.

Standard Chemseal 59: In a 1 gallon sleeve, 1% v/v Chemseal 59 (acidicsealer available from PPG) was prepared at pH=4.2.

Cerium Chloride (experimental pretreatment composition): To a 2 litervessel of deionized water was added 3 grams cerium (III) chlorideheptahydrate (available from Acros Organics) and 6 grams 29-32% hydrogenperoxide (available from Alfa Aesar).

Test Panel Preparation

Aluminum alloy 6061 panels (ACT Test Panels, LLC) were cut in half tomake panel size 4″×6″. For each set, two 6061 aluminum panels were firstcleaned as follows: All testing panels were spray cleaned in a stainlesssteel spray cabinet using Vee-jet nozzles at 10 to 15 psi, using a10-gallon bath of the Standard Ultrax14AWS Cleaner described above fortwo minutes at a bath temperature of 49° C., followed by immersion rinsein DI water for 15 seconds and spray rinse with DI water for 15 seconds.Panels were then immersed in the AMC66AW Deoxidizer bath described aboveat a 49° C. bath temperature for 1 minute, followed by spray rinse withDI water for 15 seconds.

Panels were then introduced into the pretreatment baths detailed above.

Set 1: Panels were immersed in the X-Bond (XB) pretreatment bath for 2minutes at a bath temperature of 80° F.

Set 2: Panels were immersed in the Cerium Chloride pretreatment bath for2 minutes at ambient temperature.

Set 3: Panels were immersed in the Cerium Chloride pretreatment bath for2 minutes at ambient temperature followed by immersion in the Chemseal59 bath for 1 minute at ambient temperature.

All panels then were spray rinsed with DI water for 20-30 seconds.Panels were warm air dried using a Hi-Velocity handheld blow-dryer madeby Oster® (model number 078302-300-000) on high-setting at a temperatureof about 50-55° C. until the panel was dry (about 1-5 minutes).

After drying, the conversion coating was measured by X-ray fluorescence(X-Met 7500, Oxford Instruments; operating parameters 60 second timedassay, 15 kV, 45 μA, filter 3, T(p)=1.1 μs for lanthanides). Due toprofile of the output, non-lanthanide conversion coatings do not have abaseline of zero counts and therefore, the difference between measuredcounts and baseline, not the absolute value of counts, was indicative ofthe coating's composition. The results are reported in Table 4.1.

TABLE 4.1 XRF Measurements of Ce Lα. Set Counts (kps) 1 455 2 1150 31190

Remaining panels were coated with powder coating Enviracryl® PCC10103(acrylic coating available from PPG) to a thickness of 2.75 mil.

The coated panels were tested for scribe creep blistering using theASTM-B 368-09 Copper Acetic Acid Salt Spray, to measure scribe creep.Scribe creep is measured from affected paint to affected paint to theleft and right of the scribe. The scribe is placed into the panel priorto being placed into the cabinet for a length of 10 days or 240 hours.Below is a table of scribe creep measurements from the average of twotesting panels, measured at seven points evenly spaced along a 4-inchscribe. The measurements were recorded using a Fowler Sylvac digitalcaliper Model S 235.

Panels were tested for filiform corrosion using SAE J2635 method. Scribecreep is measured from affected paint to affected paint to the left orto the right of the scribe. The scribe is placed into the panel prior toinitiation and subsequently placed into a humidity cabinet for 28 days.Below is a table of scribe creep measurements from the average of twopanels per set, measured at seven points evenly spaced along a 4-inchscribe.

Panels were subjected to crosshatch adhesion testing after 1 day soakingin a water bath heated to 60° C. Panels were allowed to recover for 20minutes in ambient conditions. With a razor blade and a Gardco Temper IIGauge tool, eleven cuts spaced 1.5 mm apart were made perpendicular toanother eleven cuts spaced 1.5 mm apart. Fibrous tape was adhered to thearea and quickly pulled away. Paint adhesion was rated on a scale of 1(no remaining paint adhesion) to 10 (perfect adhesion).

TABLE 4.2 Corrosion and Adhesion Results. CASS Avg SAE J2635 CrosshatchScribe Creep Avg Scribe Adhesion Set (mm) Creep (mm) Rating 1 2.36 (13%)0.255 (63%) 7 (42%) 2 3.07 (33%) 0.180 (47%) 6 (67%) 3 2.04 0.095 10

The data in Table 4.2 demonstrate at least a 13% decrease in scribecreep on panels treated with the system of the present inventioncompared to panels treated only with a cerium conversion composition oronly a zirconium composition as measured by CASS testing. Furthermore,the data in Table 4.2 demonstrate at least a 47% decrease in scribecreep on panels treated with the system of the present invention (i.e.,cerium conversion composition followed by zirconium-containingconversion composition) compared to panels treated only with a ceriumconversion composition or only a zirconium composition as measured bySAE J2635 testing. Finally, the data in Table 4.2 demonstrate at least a42% increase in crosshatch adhesion on panels treated with the system ofthe present invention (i.e., cerium conversion composition followed byzirconium-containing conversion composition) compared to panels treatedonly with a cerium conversion composition or only a zirconiumcomposition.

Example 5 Bath Compositions

Standard ChemKleen 2010LP/181ALP Cleaner: The bath was prepared at 1.25%v/v concentration of Chemkleen 2010LP (a phosphate-free alkaline cleaneravailable from PPG) and 0.125% of Chemkleen 181 ALP (a phosphate-freeblended surfactant additive, available from PPG) in deionized water. Forspray cleaning, a 10-gallon bath was prepared.

ChemDeox395: An acidic deoxidizer (pH 2.5) was prepared from ahexafluorosilicic acid, ammonium bifluoride, and sodium hydroxide.

Control Zircobond 1.5 (commercially available zirconium pretreatmentcomposition): To 5 gallons of deionized water was added 19.16 grams 45%hexafluorozirconic acid (available from Honeywell International Inc.),35.09 grams of a 2% by weight copper solution (prepared by dissolvingcopper nitrate hemipentahydrate, available from Fisher Scientific, indeionized water), 14 grams of Chemfos AFL (available from PPG), and 32grams of Chemfil Buffer (available from PPG). The resultant solution hada pH of 4.61 and 91.2 ppm of free fluoride.

Standard Chemseal 59: In 1-gallon sleeve, 1% v/v Chemseal 59 (acidicsealer available from PPG) was prepared at pH=4.2.

Cerium Chloride Pretreatment Composition: To a 2-liter vessel ofdeionized water was added 3 grams cerium (III) chloride heptahydrate(available from Acros Organics) and 6 grams 29-32% hydrogen peroxide(available from Alfa Aesar).

Test Panel Preparation

Aluminum alloy 6061 panels (ACT Test Panels, LLC) were cut in half tomake panel size 4″×6″. For each set, two 6061 aluminum panels were firstcleaned as follows: All testing panels were spray cleaned in a stainlesssteel spray cabinet using Vee-jet nozzles at 10 to 15 psi, using thestandard ChemKleen 2010LP/181ALP cleaner bath detailed above for twominutes at a bath temperature of 49° C., followed by immersion rinse inDI water for 15 seconds and spray rinse with DI water for 15 seconds.Panels were then immersed in ChemDeox395 at a bath temperature of 90° F.with high agitation for 1 min, followed by spray rinse with DI water for15 seconds.

Panels were then introduced into the pretreatment baths detailed above:

Set 4: Panels were immersed in the Zircobond 1.5 pretreatment bath for 2minutes at a bath temperature of 80° F.

Set 5: Panels were immersed in the cerium chloride pretreatment bath for2 minutes at ambient temperature.

Set 6: Panels were immersed in the cerium chloride pretreatment bath for2 minutes at ambient temperature followed by immersion in the Chemseal59 bath for 1 minute at ambient temperature.

All pretreated panels then were spray rinsed with DI water for 20-30seconds and warm air dried using a Hi-Velocity handheld blow-dryer madeby Oster® (model number 078302-300-000) on high-setting at a temperatureof about 50-55° C. until the panel was dry (about 1-5 minutes).

After drying, conversion coating was measured by X-ray fluorescence(X-Met 7500, Oxford Instruments; operating parameters 60 second timedassay, 15 kV, 45 μA, filter 3, T(p)=1.1 μs for lanthanides). Due toprofile of the output, non-lanthanide conversion coatings do not have abaseline of zero counts and therefore, the difference between measuredcounts and baseline, not the absolute value of counts, was indicative ofthe coating's composition.

TABLE 5.1 XRF Measurements of Ce Lα. Set Counts (kps) 4 218 5 2160 62090

After drying, the panels were electrocoated with ED7000Z electrocoat,available from PPG. The electrocoat was applied to target a 0.60 milthickness. The rectifier (Xantrex Model XFR600-2) was set to the“Coulomb Controlled” setting. The conditions were set with 22 Coulombsfor Set 4 (zirconium) and 21 Coulombs for Set 5 (cerium chloride) andSet 6 (cerium chloride and seal), 0.5 amp limit, voltage set point of200 V, and a ramp time of 30s. The electrocoat was maintained at a bathtemperature of 90° F., with a stir speed of 320 rpm. After theelectrocoat was applied, the panels were baked in an oven (DespatchModel LFD-1-42) at 177° C. for 25 minutes. The coating thickness wasmeasured using a film thickness gauge (Fischer Technology Inc. ModelFMP40C).

The coated panels were tested for scribe creep blistering using theASTM-B 368-09 Copper Acetic Acid Salt Spray, to measure scribe creep.Scribe creep is measured from affected paint to affected paint to theleft and right of the scribe. The scribe is placed into the panel priorto being placed into the cabinet for a length of 20 days or 480 hours.Below is a table of scribe creep measurements from the average of twotesting panels per set, measured at seven points evenly spaced along a4-inch scribe. The measurements were recorded using a Fowler Sylvacdigital caliper Model S 235.

Panels were tested for filiform corrosion for 6 weeks. Panels wereplaced horizontally in a desicator containing a thin layer of 12 Nhydrochloric acid (HCl) for 1 hour at ambient temperature, such thatonly the HCl fumes came into contact with the sample, within 5 minutes,the panels were placed in a vertical orientation in the humidity cabinetmaintained at 40 C and 80% relative humidity for 6 weeks. Scribe creepwas measured from affected paint to affected paint to the left and rightof the scribe. Below is a table of scribe creep measurements from theaverage of two testing panels per set, measured at seven points evenlyspaced along a 4-inch scribe. The measurements were recorded using aFowler Sylvac digital caliper Model S 235.

TABLE 5.2 Corrosion results. CASS Avg Scribe Filiform Set Creep (mm)Corrosion (mm) 4 4.06 (61%) 6.41 (18%) 5 2.62 (39%) 5.82 (10%) 6 1.605.24

The data in Table 5.2 demonstrate at least a 39% decrease in scribecreep on electrocoated panels treated with the system of the presentinvention compared to panels treated only with a cerium conversioncomposition or only a zirconium composition as measured by CASS testing.Furthermore, the data in Table 5.2 demonstrate at least a 10% decreasein scribe creep on electrocoated panels treated with the system of thepresent invention compared to panels treated only with a ceriumconversion composition or only a zirconium composition as measured byfiliform corrosion testing.

Example 6

To a 2 liter vessel of deionized water was added 3 Grams Cerium (III)Chloride Heptahydrate (Available from Acros Organics) and 5 Grams 29-32%Hydrogen Peroxide (Available from Alfa Aesar). The temperature of thebath was ambient, and the bath was still when the panel was immersed(i.e., not stirred or agitated).

In this example, 6111 aluminum panels (ACT) were evaluated fordeposition of cerium or zinc phosphate and for coloration of thepretreated panels.

4″×12″ panels of 6111 Aluminum (available from ACT Test Panels, LLC,product no. 39279) were cut in half to make panels of 4″×6″.

For each set, one half 6111 Aluminum panel was cleaned by spray cleaningin a stainless steel spray cabinet using Vee-jet nozzles at 10 to 15psi, using Cleaner 2 for two minutes at 120° F., followed by animmersion rinse in deionized water for 15 seconds and then a spray rinsewith deionized water for 15 seconds using the Melnor Rear-Trigger7-Pattern nozzle set to shower mode described above. Panels were thenintroduced into one of the conversion composition baths described aboveas follows:

Set 10—Panels were immersed in a bath containing Conversion Composition4 (bath ambient) for 2 minutes. Panels then were spray rinsed withdeionized water for 20-30 seconds using the Melnor Rear-Trigger7-Pattern nozzle set to shower mode described above. Panels were warmair dried using the Hi-Velocity handheld blow-dryer made by Oster®described above on high-setting at a temperature of 50 C-55 C until thepanel was dry (1 minute to 5 minutes).

Panel Set 12 was a comparative panel aluminum 6111 zinc phosphatetreated panel purchased from ACT Test Panels (Product No. 42606, ACTZinc Phosphate 6111AA panel) and was heated as described below forcolorimeter data.

Panels were analyzed for deposition of cerium, phosphorous, and zincusing X-ray fluorescence (measured using X-Met 7500, Oxford Instruments;operating parameters for cerium 60 second timed assay, 15Kv, 45 μA,filter 3, T(p)=1.1 μs; operating parameters for phosphorus 60 secondtimed assay, 25Kv, 20 μA, filter 1, T(p)=1.1 μs; operating parametersfor zinc 60 second timed assay, 15Kv, 45 μA, filter 3, T(p)=1.1 μs).Data are reported in Table 5, with each reported value being the averageof two measurements taken at different positions on each panel.

TABLE 6.1 XRF measurements (Example 6) Element Set 10 Set 12 Cerium (La)2197 297 Phosphorus 12 653 (Ka) Zinc (Ka) 1750 36895

Panels also were measured for yellowness of the panels followingconversion composition (measured using an X-rite Ci7800 Colorimeter, 25mm aperture). Data are reported in Table 6, with each reported valuebeing the average of two measurements taken at the same position on thepanel. Data reported are Spectral Component Excluded.

TABLE 6.2 Spectral Analysis Prior to Heating Panels (Example 6) Set L*a* b* C* h^(o) YI-E313¹ 12 74.41 0.25 2.69 2.70 84.64 6.51 10 75.23−3.72 11.42 12.01 108.02 21.50 ¹Yellowness index measurement accordingto ASTM E313-00

Next, panels were baked in an oven (Despatch Model LFD-1-42) at 177° C.for 25 minutes (panels were not electrocoated). The panels were measuredfor yellowness of the panels heating of the pretreated panels (measuredusing an Xrite Ci7800 Colorimeter, 25 mm aperture). Data are reported inTable 6.3, with each reported value being the average of twomeasurements taken at the same position on the panel. Data reported areSpectral Component Excluded.

TABLE 6.3 Spectral Analysis After Heating Panels (Example 6) Set L* a*b* C* h^(o) YI-E313² 12 74.49 0.65 3.09 3.16 78.07 7.81 10 74.46 −0.862.08 2.25 112.38 4.06

The b* value and YI-E313 value of panels pretreated only with thecerium-containing composition had increased b* value compared to zincphosphate treated panels, indicating that the cerium-treated panel had amore yellow coloration. Notably, the b* value and YI-E313 value weresignificantly lower in heated panels pretreated with cerium onlycompared to unheated panels pretreated in the same way, indicating thatheating of the panels further reduces the yellow coloration of thepanels. Furthermore, the b* and YI-E313 value of panels pretreated withthe cerium-containing composition were lower after heating panelscompared to untreated and heat panels treated with conventional zincphosphate.

We claim:
 1. A system for treating a substrate comprising: a firstcomposition for contacting at least a portion of the substrate, thefirst composition comprising a lanthanide series element cation and anoxidizing agent.
 2. The system of claim 1, wherein the oxidizing agentis present in the first composition in an amount of 25 ppm to 25,000 ppmbased on total weight of the first composition.
 3. The system of claim1, wherein the lanthanide series element cation comprises cerium,praseodymium, or combinations thereof.
 4. The system of claim 1, whereinthe lanthanide series element cation is present in the first compositionin an amount of 50 ppm to 200 ppm (calculated as cation) based on totalweight of the first conversion composition.
 5. The system of claim 1,further comprising a second composition for treating at least a portionof the substrate, the second composition comprising a Group IA metalcation.
 6. The system of claim 5, wherein the Group IA metal cationcomprises lithium, sodium, potassium, or combinations thereof.
 7. Thesystem of claim 5, wherein the Group IA metal cation is present in thesecond composition in an amount of 5 ppm to 30,000 ppm (as metal cation)based on a total weight of the second composition.
 8. The system ofclaim 5, wherein the second composition has a pH of 8 to
 13. 9. Thesystem of claim 1, further comprising a third composition for treatingat least a portion of the substrate, the second composition comprising aGroup IVB metal cation.
 10. The system of claim 9, wherein the Group IVBmetal cation comprises zirconium, titanium, or combinations thereof. 11.The system of claim 9, wherein the Group IVB metal cation is present inthe third composition in an amount of 110 ppm to 170 ppm (as metalcation) based on a total weight of the third composition.
 12. The systemof claim 9, wherein the third composition has a pH of 4 to
 5. 13. Thesystem of claim 1, wherein the system is substantially free ofphosphate.
 14. A substrate treated with the system of claim
 1. 15. Thesubstrate of claim 14, wherein the substrate treated with the system hasat least a 5% decrease in scribe creep on the substrate surface comparedto a substrate treated with a composition comprising zirconium asmeasured by CASS testing.
 16. The substrate of claim 14, wherein atleast a portion of the substrate surface is sanded, and wherein thesubstrate treated with the system has at least a 55% decrease in scribecreep on the sanded substrate surface compared to a sanded substratetreated with a composition comprising zirconium as measured by filiformcorrosion testing.
 17. The substrate of claim 14, wherein at least aportion of the substrate surface is sanded, and wherein the substratetreated with the system has at least a 78% decrease in scribe creep onthe sanded substrate surface compared to a sanded substrate treated witha composition comprising zirconium as measured by ASTM G85 A2 corrosiontesting.
 18. A substrate treated with the system of claim
 5. 19. Thesubstrate of claim 18, wherein the substrate treated with the system hasat least a 25% decrease in scribe creep on the substrate surfacecompared to a substrate treated with a composition comprising zirconiumas measured by ASTM G85 A2 testing.
 20. The substrate treated with thesystem of claim
 9. 21. The substrate of claim 20, wherein the substratetreated with the system has at least one of the following: a 13%decrease in scribe creep on the substrate surface compared to asubstrate treated with a composition comprising a lanthanide serieselement cation or a Group IVB metal cation but not both as measured byCASS testing; a 47% decrease in scribe creep on the substrate surfacecompared to a substrate treated with a composition comprising alanthanide series element cation or a Group IVB metal cation but notboth as measured by SAE J2635; and/or at least a 42% increase incrosshatch adhesion compared to a substrate treated with a compositioncomprising a lanthanide series element cation or a Group IVB metalcation but not both.
 22. A method of treating a substrate comprising:contacting at least a portion of the substrate surface with a firstcomposition comprising a lanthanide series element cation and anoxidizing agent.
 23. The method of claim 22, wherein the substratesurface is contacted with the first composition to result in a level ofthe lanthanide series element cation on the contacted substrate surfaceof at least 100 counts greater than on a surface of a substrate that isnot contacted with the first composition as measured by X-rayfluorescence (measured using X-Met 7500, Oxford Instruments; operatingparameters 60 second timed assay, 15Kv, 45 μA, filter 3, T(p)=1.5 μs).24. The method of claim 22, further comprising contacting at least aportion of the substrate surface with a second composition comprising aGroup IA metal cation and/or a Group IVB metal cation.
 25. The method ofclaim 24, wherein the contacting with the first composition occurs priorto the contacting with the second composition.
 26. The method of claim24, wherein the contacting with the second composition occurs prior tothe contacting with the first composition.
 27. The method of claim 22,wherein the contacting with the first composition is 15 seconds to 4minutes.
 28. The method of claim 22, further comprising heating thesubstrate for 15 minutes to 30 minutes at a temperature of 110° C. to232° C.
 29. A substrate treated according to the method of claim 28,wherein the substrate has a b* value of less than 3.09 (spectralcomponent excluded, 25 mm aperture).